Piston machine apparatus, and method of varying a volume of a chamber of the apparatus

ABSTRACT

A method of varying a volume of a chamber defined by a first rotor, a second rotor, and a piston in a housing of a piston machine apparatus involves: causing the first rotor to rotate around a first axis of rotation; causing the second rotor to rotate around a second axis of rotation different from the first axis of rotation; and causing the piston to slide, in response to rotation of the second rotor around the second axis of rotation, along a first linear path relative to a first coupling portion of the first rotor coupled to the piston. Causing the second rotor to rotate around the second axis of rotation involves causing a second coupling portion of the second rotor coupled to the piston to revolve around the second axis of rotation in a path around the first coupling portion. Piston machine apparatuses and uses thereof are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and priority to Canadian patent application no. 2,818,509 filed on Jun. 14, 2013, the entire contents of which are incorporated by reference herein.

FIELD

This disclosure relates generally to a piston machine apparatus, and to a method of varying a volume of a chamber of the apparatus.

RELATED ART

One known machine includes a disc mounted on a main shaft of the machine, an eccentrically mounted drum, and a curved flap hinged to the disc and to the drum. An entry port is almost tangential to a circumference of the drum, and fluid from the entry port can impinge on, and press, the flap to cause rotation of the disc and of the drum, and thus of the main shaft. As the disc and the drum rotate, the flap moves towards a recess defined by the drum, and then to a position in front of the entry port, whereby a cycle of operations is repeated. As such, the machine can function as a turbine, a pump, or the like. However, because the flap is hinged to the disc and to the drum and pivots relative to the drum towards and away from the recess defined by the drum, the drum rotates at uneven angular speed, rotating relatively fast as the flap moves towards the recess defined by the drum and relatively slowly as the flap moves away from the recess defined by the drum. Such repeated increase and decrease in angular speed of the drum can disadvantageously cause instability and wear in such a machine.

SUMMARY

According to one illustrative embodiment, there is provided a method of varying a volume of a chamber defined by a first rotor, a second rotor, and a piston in a housing of a piston machine apparatus. The method involves: causing the first rotor to rotate around a first axis of rotation; causing the second rotor to rotate around a second axis of rotation different from the first axis of rotation; and causing the piston to slide, in response to rotation of the second rotor around the second axis of rotation, along a first linear path relative to a first coupling portion of the first rotor coupled to the piston. Causing the second rotor to rotate around the second axis of rotation involves causing a second coupling portion of the second rotor coupled to the piston to revolve around the second axis of rotation in a path around the first coupling portion.

Causing the piston to slide along the first linear path may involve maintaining a relative orientation of the piston relative to the first rotor.

The method may further involve causing the piston to slide along a second linear path relative to the second coupling portion in response to rotation of the first rotor around the first axis of rotation and in response to rotation of the second rotor around the second axis of rotation.

The second linear path may extend generally parallel to a plane of rotation of the second rotor and generally perpendicular to a radius perpendicular to the second axis of rotation.

Causing the piston to slide along the first linear path may involve varying a separation distance between the second path and the first axis of rotation.

Causing the piston to slide along the second linear path relative to the second coupling portion may involve causing the piston to slide along the second linear path between the second coupling portion and a third coupling portion of the second rotor opposite and spaced apart from the second coupling portion and coupled to the piston.

The first linear path may extend generally parallel to a plane of rotation of the first rotor and generally perpendicular to a radius perpendicular to the first axis of rotation.

The first linear path may extend generally parallel to a plane of rotation of the first rotor and at an acute angle to a radius perpendicular to the first axis of rotation.

Varying the volume of the chamber may involve expanding the chamber when the chamber is in fluid communication with a fluid inlet defined by the housing of the piston machine.

Expanding the chamber may involve revolving the second coupling portion away from the inlet along the path around the first coupling portion.

The method may further involve controlling fluid flow through the fluid inlet in response to rotation of the first rotor around the first axis of rotation.

The method may further involve controlling fluid flow through the fluid inlet in response to rotation of the second rotor around the second axis of rotation.

Varying the volume of the chamber may involve contracting the chamber when the chamber is in fluid communication with a fluid outlet defined by the housing of the piston machine.

Contracting the chamber may involve revolving the second coupling portion towards the outlet along the path around the first coupling portion.

The method may further involve controlling fluid flow through the fluid outlet in response to rotation of the first rotor around the first axis of rotation.

The method may further involve controlling fluid flow through the fluid outlet in response to rotation of the second rotor around the second axis of rotation.

Varying the volume of the chamber may involve causing movement of: at least one surface of the first rotor that defines the chamber and that intersects a plane through the chamber and perpendicular to the first and second axes of rotation; at least one surface of the second rotor that defines the chamber and that intersects the plane through the chamber and perpendicular to the first and second axes of rotation; and at least one surface of the piston that defines the chamber and that intersects the plane through the chamber and perpendicular to the first and second axes of rotation.

Varying the volume of the chamber may involve varying a fluid barrier that may extend from a location where the first rotor contacts the housing to a location where the second rotor contacts the housing.

According to another illustrative embodiment, there is provided a piston machine apparatus. The apparatus includes: a housing defining a fluid inlet and a fluid outlet; a piston in the housing; a first rotor including a first coupling portion coupled to the piston, the first rotor rotatable in the housing around a first axis of rotation; and a second rotor including a second coupling portion coupled to the piston, the second rotor rotatable in the housing around a second axis of rotation different from the first axis of rotation. The second coupling portion has a position that revolves around the second axis of rotation in a path around the first coupling portion in response to rotation of the second rotor around the second axis of rotation. The piston is slidable along a first linear path relative to the first coupling portion in response to rotation of the second rotor around the second axis of rotation. The first rotor, the second rotor, and the piston are positionable to define a first chamber, in fluid communication with the fluid inlet, that expands in volume in response to revolving the second coupling portion in the path around the first coupling portion and away from the fluid inlet. The first rotor, the second rotor, and the piston are also positionable to define a second chamber, different from the first chamber and in fluid communication with the fluid outlet, that contracts in volume in response to revolving the second coupling portion in the path around the first coupling portion and towards the fluid outlet.

The piston and the first coupling portion may maintain a relative orientation of the piston relative to the first rotor when the piston slides along the first linear path relative to the first coupling portion in response to rotation of the second rotor around the second axis of rotation.

The piston may be slidable along a second linear path relative to the second coupling portion in response to rotation of the first rotor around the first axis of rotation and in response to rotation of the second rotor around the second axis of rotation.

The second linear path may extend generally parallel to a plane of rotation of the second rotor and generally perpendicular to a radius perpendicular to the second axis of rotation.

Rotation of the first rotor around the first axis of rotation and rotation of the second rotor around the second axis of rotation may vary a separation distance between the second linear path and the first axis of rotation, and may cause the piston to slide along the first linear path.

The second rotor may include a third coupling portion opposite and spaced apart from the second coupling portion and coupled to the piston. The piston may be slidable along the second linear path between the second and third coupling portions.

The first linear path may extend generally parallel to a plane of rotation of the first rotor and generally perpendicular to a radius perpendicular to the first axis of rotation.

The first linear path may extend generally parallel to a plane of rotation of the first rotor and at an acute angle to a radius perpendicular to the first axis of rotation.

The piston may include first and second opposite and non-parallel side edges. The piston may be coupled to the first coupling portion such that the first side edge is slidable along the first linear path, and the piston may be coupled to the second coupling portion such that the second side edge is slidable along the second linear path.

The housing may define a generally annular inner surface.

The first rotor may include a curved outer surface positioned to slide, in response to rotation of the first rotor around the first axis of rotation, along a first portion of the generally annular inner surface of the housing between the fluid inlet and the fluid outlet.

The second rotor may include a curved outer surface proximate the second coupling portion and positioned to slide, in response to rotation of the second rotor around the second axis of rotation, along a second portion of the generally annular inner surface of the housing.

The first rotor may define a recess sized to receive at least a portion of the piston.

The first rotor may define a recess having a position that controls fluid flow through the fluid inlet in response to rotation of the first rotor around the first axis of rotation.

The first rotor may define a recess having a position that controls fluid flow through the fluid outlet in response to rotation of the first rotor around the first axis of rotation.

The second rotor may define a recess having a position that controls fluid flow through the fluid inlet in response to rotation of the second rotor around the second axis of rotation.

The second rotor may define a recess having a position that controls fluid flow through the fluid outlet in response to rotation of the second rotor around the second axis of rotation.

At least one surface of the first rotor, at least one surface of the second rotor, and at least one surface of the piston may intersect a common plane through the first and second chambers and perpendicular to the first and second axes of rotation.

The first rotor, the second rotor, and the piston may be positionable to define the first chamber with surfaces including the at least one surface of the first rotor, the at least one surface of the second rotor, and the at least one surface of the piston.

The first rotor, the second rotor, and the piston may be positionable to define the second chamber with surfaces including the at least one surface of the first rotor, the at least one surface of the second rotor, and the at least one surface of the piston.

The first rotor, the second rotor, and the piston may define a fluid barrier that may extend from a location where the first rotor contacts the housing to a location where the second rotor contacts the housing.

The first chamber may expand in volume in response to varying the fluid barrier.

The second chamber may contract in volume in response to varying the fluid barrier.

According to another illustrative embodiment, there is provided use of the apparatus to pump a fluid.

According to another illustrative embodiment, there is provided a method of pumping a fluid. The method involves causing the first rotor of the apparatus to rotate around the first axis of rotation.

According to another illustrative embodiment, there is provided a method of pumping a fluid. The method involves causing the second rotor of the apparatus to rotate around the second axis of rotation.

Other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of illustrative embodiments in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a piston machine apparatus according to an illustrative embodiment;

FIG. 2 is a perspective view of a first end body of the apparatus of FIG. 1;

FIG. 3 is a perspective view of a first rotor of the apparatus of FIG. 1;

FIG. 4 is a plan view of the first rotor of the apparatus of FIG. 1;

FIG. 5 is a perspective view of an intermediate body of the apparatus of FIG. 1;

FIG. 6 is a first perspective view of a piston of the apparatus of FIG. 1;

FIG. 7 is a second perspective view of the piston of FIG. 6;

FIG. 8 is a plan view of a second rotor of the apparatus of FIG. 1;

FIG. 9 is a perspective view of the second rotor of the apparatus of FIG. 1;

FIG. 10 is an assembled perspective view of the apparatus of FIG. 1;

FIG. 11 is a cross-sectional view of the apparatus of FIG. 1, taken along the lines XI-XI in FIGS. 10 and 12;

FIG. 12 is a cross-sectional view of the apparatus of FIG. 1, taken along the line XII-XII in FIG. 10;

FIG. 13 is a cross-sectional view of the apparatus of FIG. 1, showing rotation of the first and second rotors relative to the positions shown in FIG. 12;

FIG. 14 is a cross-sectional view of the apparatus of FIG. 1, showing further rotation of the first and second rotors relative to the positions shown in FIG. 13;

FIG. 15 is a cross-sectional view of the apparatus of FIG. 1, showing further rotation of the first and second rotors relative to the positions shown in FIG. 14;

FIG. 16 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 17 is a first perspective view of a piston of the apparatus of FIG. 16;

FIG. 18 is a second perspective view of the piston of FIG. 17;

FIG. 19 is a cross-sectional view of a first rotor of the apparatus of FIG. 16, taken along the line XIX-XIX in FIG. 16;

FIG. 20 is a cross-sectional view of a second rotor of the apparatus of FIG. 16, taken along the line XX-XX in FIG. 16;

FIG. 21 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 22 is a perspective view of a piston and of a first rotor of the apparatus of FIG. 21;

FIG. 23 is a perspective view of the piston and of a second rotor of the apparatus of FIG. 21;

FIG. 24 is a first exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 25 is a second exploded perspective view of the apparatus of FIG. 24;

FIG. 26 is a first exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 27 is a second exploded perspective view of the apparatus of FIG. 26;

FIG. 28 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 29 is an assembled perspective view of the apparatus of FIG. 28;

FIG. 30 is a cross-sectional view of the apparatus of FIG. 28, taken along the line XXX-XXX in FIG. 28;

FIG. 31 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 32 is an assembled perspective view of the apparatus of FIG. 31;

FIG. 33 is a cross-sectional view of the apparatus of FIG. 31, taken along the line XXXIII-XXXIII in FIG. 31;

FIG. 34 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 35 is an assembled perspective view of the apparatus of FIG. 34; and

FIG. 36 is a cross-sectional view of the apparatus of FIG. 34, taken along the line XXXVI-XXXVI in FIG. 34;

FIG. 37 is an exploded perspective view of a piston machine apparatus according to another illustrative embodiment;

FIG. 38 is a perspective view of a first end body of the apparatus of FIG. 37;

FIG. 39 is a perspective view of a first rotor of the apparatus of FIG. 37;

FIG. 40 is a perspective view of an intermediate body of the apparatus of FIG. 37;

FIG. 41 is a cross-sectional view of the intermediate body of FIG. 40, taken along the line XLI-XLI in FIG. 40;

FIG. 42 is a perspective view of a second rotor of the apparatus of FIG. 37;

FIG. 43 is a cross-sectional view of the second rotor of FIG. 42, taken along the line XLIII-XLIII in FIG. 40;

FIG. 44 is a perspective view of a piston of the apparatus of FIG. 37;

FIG. 45 is a plan view of the piston of FIG. 44;

FIG. 46 is a cross-sectional view of the piston of FIG. 44, taken along the lines XLVI-XLVI in FIGS. 44 and 45;

FIG. 47 is an assembled perspective view of the apparatus of FIG. 37;

FIG. 48 is a cross-sectional view of the apparatus of FIG. 37, taken along the lines XLVIII-XLVIII in FIGS. 47 and 49;

FIG. 49 is a cross-sectional view of the apparatus of FIG. 37, taken along the lines XLIX-XLIX in FIGS. 47 and 48;

FIG. 50 is a cross-sectional view of the apparatus of FIG. 37, showing rotation of the first and second rotors relative to the positions shown in FIG. 49;

FIG. 51 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 50;

FIG. 52 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 51;

FIG. 53 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 52;

FIG. 54 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 53;

FIG. 55 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 54; and

FIG. 56 is a cross-sectional view of the apparatus of FIG. 37, showing further rotation of the first and second rotors relative to the positions shown in FIG. 55.

DETAILED DESCRIPTION

Referring to FIG. 1, a piston machine apparatus according to an illustrative embodiment is shown generally at 100 and includes a first end body 102, a first rotor 104, an intermediate body 106, a piston 108, a second rotor 110, and a second end body 112.

Referring to FIGS. 1 and 2, the first end body 102 is generally cylindrical and has an outer side shown generally at 114 and an inner side shown generally at 116 and opposite the outer side 114. In this context, “generally cylindrical” refers to a body that includes some surfaces of a cylinder but that may vary from a perfect cylinder as described below or for other reasons that permit functions substantially similar to those described below. More generally, “generally” herein contemplates variations that may or may not be described herein and that permit functions substantially similar to those described herein. On the outer side 114, the first end body 102 has a generally circular outer surface 118, and on the inner side 116, the first end body 102 has a generally circular inner surface 120. Through-openings shown generally at 122 and 124 extend between the surface 118 and the surface 120 of the first end body 102. Further, the surface 120 defines a generally cylindrical recess shown generally at 126 and defined by a generally circular recessed surface 128 and a generally annular surface 130 surrounding and extending away from the surface 128. The surface 128 is recessed by an axial height 132 of the surface 130. As shown in FIG. 2, a portion of the through-opening 122 extends through the surface 128, and the through-opening 122 extends across the surface 130. Otherwise, the through-opening 124, the surface 128, and the surface 130 are generally rotationally symmetric around an axis 134 of the first end body 102, and more particularly, the through-opening 124 extends by a radius 136 from the axis 134, the surface 128 extends by a radius 138 from the axis 134, and the surface 130 is spaced apart from the axis 134 by the radius 138.

Referring to FIGS. 1, 3, and 4, the first rotor 104 is generally cylindrical and has an outer side shown generally at 140 and an inner side shown generally at 142 and opposite the outer side 140. On the outer side 140, the first rotor 104 has a generally circular outer surface 144, and the first rotor 104 defines a generally cylindrical projection 146 projecting away from the surface 144. The surface 144 extends by a radius 148 from an axis 150 of the first rotor 104, and the projection 146 extends by a radius 152 from the axis 150. On the inner side 142, the first rotor 104 has a raised surface 154 and a recessed surface 156. The surface 154 and the surface 156 are generally parallel to and spaced apart from the surface 144, and a curved outer surface 157 extends around the first rotor 104 between the surface 144 and the surfaces 154 and 156. Further, the surface 154 is spaced apart from the surface 144 by an axial thickness 158, and the surface 156 is spaced apart from the surface 144 by an axial thickness 160. Accordingly, the surface 154 is spaced apart from the surface 156 by an axial thickness 162, which is a difference between the thickness 158 and the thickness 160. On the inner side 142, the first rotor 104 also has axial surfaces 164, 166, 168, and 170 extending generally parallel to the axis 150 and generally perpendicular to the surfaces 154 and 156. The surface 156 and the surfaces 164, 166, 168, and 170 define a recess shown generally at 172 in the first rotor 104. Further, in the recess 172, the first rotor 104 defines a groove shown generally at 174 in the surface 156. The groove 174 extends generally parallel to the surface 170 and at an acute angle 176 to the radius 148.

Referring back to FIGS. 1 and 2, the radius 136 is approximately equal to the radius 152, the radius 138 is approximately equal to the radius 148, and the height 132 is approximately equal to the thickness 160. In this context, “approximately equal” refers either to precisely equal or to sufficiently equal to permit functions substantially similar to those described below. More generally, “approximately” herein contemplates variations that permit functions substantially similar to those described herein. Accordingly, a disc portion 178 of the first rotor 104, namely the portion of the first rotor 104 that extends by the thickness 160 from the surface 144, may be received in the recess 126. When the disc portion 178 is received in the recess 126, the surface 144 contacts the surface 128, the axes 134 and 150 are generally collinear, a portion of the surface 157 contacts the surface 130, the projection 146 is received in the through-opening 124 and is accessible from the outer side 114 of the first end body 102, and the surfaces 120 and 156 (shown in FIGS. 3 and 4) are generally coplanar.

Referring to FIGS. 1 and 5, the intermediate body 106 is generally annular and has a first side shown generally at 180 and a second side shown generally at 182 and opposite the first side 180. The intermediate body 106 also has a first generally annular surface 184 on the first side 180, a second generally annular surface 186 on the second side 182, and a generally annular inner surface 188 extending between the surfaces 184 and 186. The surface 188 defines a first recess shown generally at 190 and extending between the surfaces 184 and 186, and a second recess shown generally at 192 and extending between the surfaces 184 and 186. In various embodiments, the surface 120 (shown in FIG. 2) may be attached to the surface 184 by one or more fasteners (such as bolts, screws, or rivets, for example), by complementary threads (not shown) on the surfaces 120 and 184, by welding, by soldering, or by adhesive, for example, and the first recess 190 is positioned to be in fluid communication with the through-opening 122 when the surface 120 is attached to the surface 184.

The first and second recesses 190 and 192 divide the surface 188 into a first curved portion 194 and a second curved portion 196. The first curved portion 194 extends along an arc of a circle 198 extending by a radius 200 around an axis 202, and the second curved portion 196 extends along an arc of a circle 204 extending by a radius 206 around an axis 208. The radius 200 is smaller than the radius 206, and the axis 202 is generally parallel to but spaced apart (or different) from the axis 208. Further, the axis 202 extends between the axis 208 and the first curved portion 194. Consequently, the first recess 190 is not opposite the second recess 192, and an arc length 210 of the first curved portion 194 is less than an arc length 212 of the second curved portion 196. Further, the radius 200 is approximately equal to the radius 148, so when a portion of the surface 157 is positioned against the first curved portion 194, the axes 150 and 202 are generally collinear, the portion of the surface 157 closely contacts at least portion of the first curved portion 194, and portions of the surface 157 slide along the first curved portion 194 along the arc length 210 in response to rotation of the first rotor 104 around the axis 150.

Referring to FIGS. 6 and 7, the piston 108 has a first generally planar surface 214 and a second generally planar surface 216 opposite and generally parallel to the first surface 214. The piston 108 also has side surfaces 218, 220, 222, 224, and 226 extending between the first and second surfaces 214 and 216. The piston 108 defines a first elongate projection 228 extending away from the first surface 214 and along the surface 218, and a second elongate projection 230 extending away from the second surface 216 and along the surface 224. The surfaces 218 and 224 extend non-parallel to each other, so the first and second projections 228 and 230 also extend along directions non-parallel to each other. Other than the first and second projections 228 and 230, the piston 108 has an axial thickness 232 that is approximately equal to the thickness 162 shown in FIGS. 1 and 3, and the surfaces 218, 220, and 222 are sized to abut the surfaces 166, 168, and 170 (shown in FIGS. 3 and 4) respectively when a portion of the piston 108 including the surfaces 218, 220, and 222 is received in the recess 172 (shown in FIGS. 1, 3, and 4). The recess 172 is thus sized to receive such a portion of the piston 108.

Referring to FIGS. 1, 3, 4, and 6, the first projection 228 is sized to be received in the groove 174 (shown in FIGS. 3 and 4) so that when the first projection 228 is received in the groove 174, the piston 108 can slide relative to the first rotor 104 in a first linear path defined by the groove 174, namely in a direction generally parallel to the surface 170 and generally parallel to a plane of rotation of the first rotor 104. Accordingly, the piston 108 may be coupled to the first rotor 104 at the groove 174, so the portion of the first rotor 104 defining the groove 174 is a first coupling portion of the first rotor 104 and the piston 108 can slide along the first linear path relative to the first coupling portion.

Further, the first projection 228 is longer than a width of the groove 174, so when the first projection 228 is positioned in the groove 174, the first projection 228 and the groove 174 cooperate to prevent rotation of the piston 108 relative to the first rotor 104. In other words, the first projection 228 and the groove 174 permit the piston 108 to slide relative to the first rotor 104 and maintain a relative orientation of the piston 108 relative to the first rotor 104 by maintaining the surface 218 generally parallel to the surface 170. Herein, expressions such as “prevent rotation” and “maintain a relative orientation” may refer to maintaining a precise relative orientation, or to permitting some changes to the relative orientation (for example, due to differences between a thickness of the first projection 228 and a width of the groove 174, or to curves in the groove 174) while maintaining functions substantially similar to those described herein. Further, the groove 174 and the first projection 228 are positioned such that when the first projection 228 is received in the groove 174, the surface 218 is held against the surface 170.

Referring to FIGS. 1, 8, and 9, the second rotor 110 includes a generally cylindrical portion 234 having an axial thickness 235 and extending by a radius 236 from an axis 238, except for a recess shown generally at 239 at a periphery of the generally cylindrical portion 234. The second rotor 110 has a first side shown generally at 240 and a second side shown generally at 242 and opposite the first side 240, and the second rotor 110 defines a projection 244 on the first side 240 projecting away from the generally cylindrical portion 234. The projection 244 also has a curved outer surface 246 facing away from the axis 238 and extending away from the generally cylindrical portion 234 at a radius 248 from the axis 238. The radius 248 is less than the radius 236. The projection 244 has a generally planar axial surface 250 facing towards the axis 238 and extending away from the generally cylindrical portion 234 generally perpendicular to the radius 248. Further, on the first side 240, the second rotor 110 defines a groove shown generally at 252, which extends generally parallel to the surface 250 and generally perpendicular to the radius 248. On the second side 242, the second rotor 110 defines a generally cylindrical projection 254 projecting away from the generally cylindrical portion 234 and extending by a radius 256 from the axis 238.

Referring to FIGS. 1 and 7 to 9, the second projection 230 is sized to be received in the groove 252 so that the piston 108 can slide relative to the second rotor 110 along a second linear path defined by the groove 252, namely in a direction generally parallel to the surface 250 (and thus generally perpendicular to a radius of the second rotor 110) and generally parallel to a plane of rotation of the second rotor 110 when the second projection 230 is received in the groove 252. Further, the second projection 230 is longer than a width of the groove 252, so when the second projection 230 is positioned in the groove 252, the second projection 230 and the groove 252 cooperate to prevent rotation of the piston 108 relative to the second rotor 110. In other words, the second projection 230 and the groove 252 permit the piston 108 to slide relative to the second rotor 110 and maintain a relative orientation of the piston 108 relative to the second rotor 110 by maintaining the surface 224 generally parallel to the surface 250. Further, the groove 252 and the second projection 230 are positioned such that when the second projection 230 is received in the groove 252, the surface 224 is held against the surface 250. Accordingly, the piston 108 may be coupled to the second rotor 110 at the groove 252, so the portion of the second rotor 110 defining the groove 252 is a second coupling portion of the second rotor 110 proximate the surface 246, the piston 108 can slide along the second linear path relative to the second coupling portion, and the second coupling portion of the second rotor 110 revolves around the axis 238 and in a path around the first coupling portion (namely, the portion of the first rotor 104 defining the groove 174 shown in FIGS. 3 and 4) when the second rotor 110 revolves around the axis 238.

Referring to FIGS. 1, 5, and 8, the radius 248 is approximately equal to the radius 206, so when the surface 246 is positioned against the second curved portion 196, the axes 238 and 208 are generally collinear and the surface 246 closely contacts a portion of the second curved portion 196 and slides along the second curved portion 196 substantially along the arc length 212 in response to rotation of the second rotor 110 around the axis 238.

Referring back to FIG. 1, the second end body 112 includes a generally cylindrical end wall 258 and a generally annular wall 260 that define a generally cylindrical recess shown generally at 262. The recess 262 has an axial height 264 and extends by a radius 266 from an axis 268 of the second end body 112. The wall 260 also defines through-openings shown generally at 270 and 272 and extending into the recess 262. The through-opening 270 is near the wall 260, and the through-opening 272 extends by a radius 274 from the axis 268. In various embodiments, the wall 260 may be attached to the surface 186 by one or more fasteners (such as bolts, screws, or rivets, for example), by complementary threads (not shown) on the wall 260 and on the surface 186, by welding, by soldering, or by adhesive, for example, and the through-opening 270 is axially aligned with the second recess 192 when the wall 260 is attached to the surface 186.

The radius 266 is approximately equal to the radius 236 and the radius 274 is approximately equal to the radius 256 (shown in FIG. 9), so the generally cylindrical portion 234 may be received in the recess 262 and positioned against the wall 258 with the projection 254 received in the through-opening 272. When the generally cylindrical portion 234 is positioned against the wall 258, the axes 238 and 268 are generally collinear, and the generally cylindrical portion 234 covers the through-opening 270 except when the generally cylindrical portion 234 is rotationally positioned such that the recess 239 is positioned over the through-opening 270. Therefore, when the wall 260 is attached to the surface 186 with the generally cylindrical portion 234 positioned against the wall 258, the through-opening 270 is positioned to be in fluid communication with the second recess 192 when the generally cylindrical portion 234 is rotationally positioned such that the recess 239 is positioned over the through-opening 270. In other words, the generally cylindrical portion 234 can control fluid flow through the through-opening 270 in response to rotation of the generally cylindrical portion 234 around the axis 238.

Referring to FIGS. 1 to 12, the apparatus 100 may be assembled by positioning the disc portion 178 in the recess 126 with the projection 146 received in the through-opening 124, by attaching the surface 120 to the surface 184 with the first recess 190 in fluid communication with the through-opening 122, by positioning the first surface 214 against the surface 156 with the first projection 228 positioned in the groove 174, by positioning the generally cylindrical portion 234 against the surface 154 with the projection 244 positioned against the surface 120 and with the second projection 230 positioned in the groove 252, and by attaching the wall 260 to the surface 186 with the generally cylindrical portion 234 positioned against the wall 258, with the projection 254 received in the through-opening 272, and with the through-opening 270 positioned to be in fluid communication with the second recess 192 when the generally cylindrical portion 234 is rotationally positioned such that the recess 239 is positioned over the through-opening 270. When the apparatus 100 is assembled as shown in FIGS. 10 to 12, the first end body 102, the intermediate body 106, and the second end body 112 collectively form a housing of the apparatus 100 and the first rotor 104, the piston 108, and the second rotor 110 are in the housing. When the apparatus 100 is assembled as shown, the axes 150 and 202 are generally collinear and the axes 238 and 208 are generally collinear, and because the axes 202 and 208 are different as indicated above, the axes 150 and 238 are also different.

Referring to FIG. 12, when the apparatus 100 is assembled as shown, the first rotor 104 can rotate around the axis 150 (which is generally collinear with the axes 134 and 202) and the second rotor 110 can rotate around the axis 238 (which is generally collinear with the axes 208 and 268). Further, as indicated above, when the apparatus 100 is assembled as shown, the first projection 228 (shown in FIGS. 1 and 6) and the groove 174 (shown in FIGS. 3 and 4) permit the piston 108 to slide relative to the first rotor 104 and maintain a relative orientation of the piston 108 relative to the first rotor 104 by maintaining the surface 218 generally parallel to the surface 170, and the second projection 230 (shown in FIGS. 1 and 7) and the groove 252 (shown in FIGS. 1, 8, and 12) permit the piston 108 to slide relative to the second rotor 110 and maintain a relative orientation of the piston 108 relative to the second rotor 110 by maintaining the surface 224 generally parallel to the surface 250. Accordingly, rotation of the first rotor 104 around the axis 150 causes rotation of the second rotor 110 around the axis 238 because when the first rotor 104 is rotated around the axis 150, the first rotor 104 exerts a force on the piston 108 to maintain the relative orientation of the piston 108 relative to the first rotor 104, and the piston 108 exerts a force on the second rotor 110 to maintain the relative orientation of the piston 108 relative to the second rotor 110. Conversely, rotation of the second rotor 110 around the axis 238 causes rotation of the first rotor 104 around the axis 150.

As indicated above with reference to FIGS. 1 and 5, the axis 202 extends between the axis 208 and the first curved portion 194, and because the axis 202 is generally collinear with the axis 150 and the axis 208 is generally collinear with the axis 238 when the apparatus 100 is assembled as shown, the axis 150 extends between the axis 238 and the first curved portion 194. Accordingly, and still referring to FIG. 12, a separation distance 276 between the surface 250 and the axis 150 varies in response to rotation of the first rotor 104 around the axis 150 and in response to rotation of the second rotor 110 around the axis 238. More particularly, the separation distance 276 is relatively small when the projection 244 is proximate the first curved portion 194 as shown in FIG. 13, the separation distance 276 is relatively large when the projection 244 is opposite the first curved portion 194 as shown in FIG. 15, and the separation distance 276 is relatively intermediate when the projection 244 is between positions that are proximate and opposite the first curved portion 194 as shown in FIGS. 12 and 14.

Because the piston 108 is coupled to the second rotor 110 at the groove 252, which extends generally parallel to the surface 250, because rotation of the second rotor 110 around the axis 238 varies the separation distance 276 between the surface 250 (and thus the surface 224 held against the surface 250) and the axis 150, and because the first rotor 104 rotates around the axis 150, rotation of the second rotor 110 around the axis 238 causes the piston 108 to slide along the first linear path defined by the groove 174 (shown in FIGS. 3 and 4), namely in the direction generally parallel to the surface 170 and generally parallel to a plane of rotation of the first rotor 104, relative to the first rotor 104. Also, because the surface 170 extends at the acute angle 176 to the radius 148 (also shown in FIGS. 3 and 4), when the piston 108 slides along the first linear path defined by the groove 174 in response to rotation of the first rotor 104 around the axis 150 and in response to rotation of the second rotor 110 around the axis 238, the piston 108 also slides along the second linear path defined by the groove 252, namely in the direction generally parallel to the surface 250 (and thus generally perpendicular to a radius of the second rotor 110) and generally parallel to a plane of rotation of the second rotor 110.

As indicated above with reference to FIGS. 1, 3, 4, 6, and 7, the surfaces 218, 220, and 222 are sized to abut the surfaces 166, 168, and 170 respectively when a portion of the piston 108 including the surfaces 218, 220, and 222 is received in the recess 172, and the groove 174 and the surface 170 extend at the acute angle 176 to the radius 148. Also, as indicated above with reference to FIGS. 1 and 7 to 9, the first projection 228 and the groove 174 permit the piston 108 to slide relative to the first rotor 104 while maintaining the surface 218 generally parallel to the surface 170, and the groove 174 and the first projection 228 hold the surface 218 against the surface 170. Therefore, when the separation distance 276 is relatively small as shown in FIG. 13, the surfaces 218, 220, and 222 abut the surfaces 166, 168, and 170 respectively, and as the separation distance 276 increases, the surface 220 becomes spaced apart from the surface 168 and the surface 222 becomes spaced apart from the surface 170.

FIG. 14 illustrates the apparatus 100 after the projection 244 rotates around the axis 238 and in the direction of the arrow 278 past the first recess 190. In the position shown in FIG. 14, the projection 244 is between positions that are proximate and opposite the first curved portion 194, so the separation distance 276 is relatively intermediate, the surface 220 is spaced apart from the surface 168, and the surface 222 is spaced apart from the surface 166. As indicated above, when the apparatus 100 is assembled as shown, a portion of the surface 157 closely contacts at least a portion of the first curved portion 194, the surface 218 is held against the surface 170, the surface 224 is held against the surface 250, and the surface 246 closely contacts a portion of the second curved portion 196. The first rotor 104, the piston 108, and the projection 244 therefore collectively define a fluid barrier extending from the portion of the surface 188 that closely contacts the portion of the surface 157 to the portion of the surface 188 that closely contacts the surface 246. In other words, the fluid barrier extends from a location on the intermediate body 106 where the portion of the surface 188 closely contacts the portion of the surface 157 to another different location on the intermediate body 106 where the portion of the surface 188 closely contacts the surface 246.

As such, when the projection 244 is in the position shown in FIG. 14, the first rotor 104, the piston 108, the second rotor 110, and the housing (including the surface 188 of the intermediate body 106) define a chamber shown generally at 280 and in fluid communication with the first recess 190, and thus in fluid communication with the through-opening 122 (shown in FIGS. 1 and 2) as indicated above. More particularly, in various positions, one or more of the surface 120 (shown in FIG. 2), the surface 156 (shown in FIGS. 3 and 4), the surfaces 164, 166, 168, and 170, the surface 188 (shown in FIGS. 1 and 5), the surfaces 220 and 222, the surface 250, and the generally cylindrical portion 234 define the chamber 280. The surfaces 164, 166, 168, 170, 220, 222, and 250 all intersect a common plane (for example, a plane including the section line XII-XII in FIG. 10) that is through the chamber 280 and that is perpendicular to the axes 150 and 238. Therefore, each of the first rotor 104, the piston 108, and the second rotor 110 has at least one surface that defines the chamber 280 in various positions, and that intersects the common plane that is through the chamber 280 and that is perpendicular to the axes 150 and 238. Also, varying the volume of the chamber 280 may involve moving at least one surface of the first rotor 104 (namely, the surfaces 164, 166, 168, and 170), at least one surface of the piston 108 (namely, the surfaces 220 and 222), and at least one surface of the second rotor 110 (namely, the surface 250) that define the chamber 280 and that also intersect the common plane that is through the chamber 280 and that is perpendicular to the axes 150 and 238. Because the surfaces 220 and 222 define the chamber 280, and because the surfaces 220 and 222 are on a trailing side (namely, a side opposite the direction of the arrow 278) of the piston 108, the chamber 280 may be referred to as a “trailing-side” chamber.

FIG. 15 illustrates the apparatus 100 after the projection 244 further rotates around the axis 238 and in the direction of the arrow 278. In general, such rotation varies the portion of the surface 188 that closely contacts the surface 246, and therefore varies the aforementioned fluid barrier defined by the first rotor 104, the piston 108, and the projection 244. Accordingly, such rotation also generally varies volumes of fluid chambers defined by the first rotor 104, the piston 108, the second rotor 110, and the housing. In the position shown in FIG. 15, the piston 108 is farther from the first recess 190 and from the axis 150, and as such, rotation of the first rotor 104 around the axis 150 and rotation of the second rotor 110 around the axis 238 cause a volume of the chamber 280 to increase. In other words, expanding the volume of the chamber 280 involves revolving the second coupling portion (the portion defining the groove 252) of the second rotor 110 around the axis 238 in the direction of the arrow 278 and in the aforementioned path around the first coupling portion (namely, the portion of the first rotor 104 defining the groove 174 shown in FIGS. 3 and 4) away from the first recess 190 in fluid communication with the chamber 280.

Referring back to FIG. 14, after the projection 244 rotates around the axis 238 and in the direction of the arrow 278 past the first recess 190, the first rotor 104, the piston 108, the second rotor 110, and the housing (including the surface 120 shown in FIG. 2 of the first end body 102 and the surface 188 of the intermediate body 106) define a chamber shown generally at 282 in fluid communication with the second recess 192. More particularly, in various positions, one or more of the surface 120 (shown in FIG. 2), the surface 157, the surface 170, the surface 188, the surfaces 218 and 226, the surface 250, and the generally cylindrical portion 234 define the chamber 282. The surfaces 157, 226, and 250 all intersect the common plane (for example, the plane including the section line XII-XII in FIG. 10) that is through the chambers 280 and 282 and that is perpendicular to the axes 150 and 238. Therefore, each of the first rotor 104, the piston 108, and the second rotor 110 has at least one surface that defines the chamber 282 in various positions, and that intersects the common plane that is through the chambers 280 and 282 and that is perpendicular to the axes 150 and 238. Also, varying the volume of the chamber 282 may involve moving at least one surface of the first rotor 104 (namely, the surface 157), at least one surface of the piston 108 (namely, the surface 226), and at least one surface of the second rotor 110 (namely, the surface 250) that define the chamber 282 and that also intersect the common plane that is through the chambers 280 and 282 and that is perpendicular to the axes 150 and 238. Because the surfaces 218 and 226 define the chamber 282, and because the surfaces 218 and 226 are on a leading side (namely, a side in direction of the arrow 278) of the piston 108, the chamber 282 may be referred to as a “leading-side” chamber. The chamber 282 is on an opposite side from the chamber 280 of the aforementioned fluid barrier defined by the first rotor 104, the piston 108, and the projection 244. More generally, the aforementioned fluid barrier fluidly isolates the chamber 280 from the chamber 282, and the chamber 282 is different from the chamber 280.

As indicated above, FIG. 15 illustrates the apparatus 100 after the projection 244 further rotates around the axis 238 and in the direction of the arrow 278. In the position shown in FIG. 15, the piston 108 is closer to the second recess 192, and as such, rotation of the first rotor 104 around the axis 150 and rotation of the second rotor 110 around the axis 238 cause a volume of the chamber 282 to decrease. In other words, contracting the volume of the chamber 282 involves revolving the second coupling portion (the portion defining the groove 252) of the second rotor 110 around the axis 238 in the direction of the arrow 278 and in the aforementioned path around the first coupling portion (namely, the portion of the first rotor 104 defining the groove 174 shown in FIGS. 3 and 4) towards the second recess 192 in fluid communication with the chamber 282.

In summary, a volume of the chamber 280 or a volume of the chamber 282 may be varied by causing the first rotor 104 to rotate around the axis 150, by causing the second rotor 110 to rotate around the axis 238 and thereby causing the second coupling portion (the portion defining the groove 252) of the second rotor 110 coupled to the piston 108 to revolve around the axis 238, which is different from the axis 150, in a path around the first coupling portion (namely, the portion of the first rotor 104 defining the groove 174 shown in FIGS. 3 and 4), and by causing the piston 108 to slide along a first linear path defined by the groove 174, namely in a direction generally parallel to the surface 170, relative to the first rotor 104 in response to rotation of the second rotor 110 around the axis 238. The aforementioned path of the second coupling portion (namely, the portion of the second rotor 110 defining the groove 252) is around the first coupling portion (namely, the portion of the first rotor 104 defining the groove 174 shown in FIGS. 3 and 4) because as the second coupling portion revolves once around the axis 238, the second coupling portion travels around all sides (from the point of view of the housing formed by the first end body 102, the intermediate body 106, and the second end body 112) of the first coupling portion.

Referring back to FIG. 12, the projection 244 is shown further rotated around the axis 238 and in the direction of the arrow 278 until the projection 244 almost reaches the second recess 192 (shown in FIGS. 1, 5, and 13 to 15). At that time, the chamber 280 is relatively large, the chamber 282 is relatively small, and the recess 239 is positioned over the through-opening 270, so the second recess 192, and thus the chamber 282, are in fluid communication with the through-opening 270.

In operation, referring to FIGS. 12 to 15, the through-opening 122 (shown in FIG. 1) may be coupled to a fluid source (not shown), and a torque may be applied to one or both of the projections 146 (shown in FIG. 1) and 254 (shown in FIG. 9) to cause the first rotor 104 to rotate repeatedly around the axis 150 in the direction of the arrow 278 and to cause the second rotor 110 to rotate repeatedly around the axis 238 in the direction of the arrow 278. In various embodiments such as those described herein, torques may be applied by one or more of different types of motors, turbines, or other torque sources (not shown) as may be appropriate. As indicated above, such rotation causes a volume of the chamber 280 (which is in fluid communication with the through-opening 122) to increase as the projection 244 moves in the direction of the arrow 278 from the position shown in FIG. 14 to the position shown in FIG. 12. Therefore, applying a torque in the direction of the arrow 278 to one or both of the projections 146 and 254 may cause a fluid (not shown) from the fluid source coupled to the through-opening 122 to be drawn into the chamber 280. The through-opening 122 may thus function as a fluid inlet.

As the projection 244 moves in the direction of the arrow 278 past the second recess 192 into the position shown in FIG. 13, the fluid drawn into the chamber 280 is in the chamber 282, namely the “leading-side” chamber in fluid communication with the second recess 192. As indicated above, rotation of the first rotor 104 around the axis 150 in the direction of the arrow 278 and rotation of the second rotor 110 around the axis 238 in the direction of the arrow 278 cause a volume of the chamber 282 to decrease. Therefore, applying a torque in the direction of the arrow 278 to one or both of the projections 146 and 254 may cause fluid that was drawn into the chamber 280 to be pressurized when in fluid communication with the second recess 192. As indicated above, when the apparatus 100 is assembled as shown, the through-opening 270 (shown in FIG. 1) is in fluid communication with the second recess 192 when the recess 239 (shown in FIGS. 1, 8, and 9) is positioned over the through-opening 270, and as indicated above, the recess 239 is positioned over the through-opening 270 when the projection 244 almost reaches the second recess 192 as shown in FIG. 12. Also as indicated above, when the projection 244 almost reaches the second recess 192 as shown in FIG. 12, the chamber 282 is relatively small, so the fluid in the chamber 282 is pressurized. As such, in response to rotation of the first rotor 104 around the axis 150 in the direction of the arrow 278, and in response to rotation of the second rotor 110 around the axis 238 in the direction of the arrow 278, pressurized fluid from the chamber 282 is communicated through the through-opening 270. The through-opening 270 may thus function as a fluid outlet.

Still referring to FIGS. 12 to 15, at least a portion of the surface 157 closely contacts at least portion of the first curved portion 194, thereby maintaining the aforementioned fluid barrier defined by the first rotor 104, the piston 108, and the projection 244, except when the projection 244 passes past the first curved portion 194 as shown in FIG. 13. However, in such positions, the fluid outlet of the apparatus 100 is closed because the recess 239 is not positioned over the through-opening 270. Therefore, in such positions, the generally cylindrical portion 234 may prevent fluid leakage from the fluid outlet of the apparatus 100 to the fluid inlet of the apparatus 100. FIG. 13 also illustrates that the surfaces 164, 166, and 170 are positioned such that the surface 157 is separated from the first curved portion 194 for a sufficient range of rotational positions of the first rotor 104 around the axis 150 to allow the projection 244 to pass past the first curved portion 194 as shown in FIG. 13. Otherwise, because the first curved portion 194 extends between the first and second recesses 190 and 192, when a portion of the surface 157 closely contacts at least portion of the first curved portion 194, the fluid barrier defined by the first rotor 104, the piston 108, and the projection 244 fluidly separates the first and second recesses 190 and 192, and thus fluidly separates the fluid inlet of the apparatus 100 from the fluid outlet of the apparatus 100.

In general, the apparatus 100 may function as a fluid pump because applying a torque in the direction of the arrow 278 to one or both of the projections 146 and 254 may cause the apparatus 100 to cycle through positions shown in FIGS. 12 to 15 and may cause a fluid from a fluid source coupled to the through-opening 122 (or fluid inlet) to be pressurized and communicated through the through-opening 270 (or fluid outlet). Further, because the first projection 228 (shown in FIGS. 1 and 6) and the groove 174 (shown in FIGS. 3 and 4) maintain a relative orientation of the piston 108 relative to the first rotor 104, and because the second projection 230 (shown in FIGS. 1 and 7) and the groove 252 maintain a relative orientation of the piston 108 relative to the second rotor 110, the first rotor 104 rotates at a relatively more consistent angular speed when compared to other piston machines, which may avoid some disadvantages of inconsistent angular speed in such other piston machines. Although not shown, one or more valves may be positioned in fluid communication with one or both of the fluid inlet and the fluid outlet.

Alternative embodiments may differ from the apparatus 100 in various ways. For example, referring to FIG. 16, a piston machine apparatus according to another illustrative embodiment is shown generally at 284 and includes a first end body 286, a first rotor 288, a piston 290, a second rotor 292, and a second end body 294. The first end body 286 is substantially the same as the first end body 102 (shown in FIGS. 1 and 2) integrally formed with the intermediate body 106 (shown in FIGS. 1 and 5), and more generally, in the various embodiments described herein, the first end bodies or the second end bodies may be integrally formed (by molding, casting, or machining, for example) with the intermediate bodies. Further, the second end body 294 is substantially the same as the second end body 112 (shown in FIG. 1).

Referring to FIGS. 16 to 18, the piston 290 is substantially the same as the piston 108 (shown in FIGS. 1, 6, 7, and 12 to 15) and has side surfaces 296, 298, 300, 302, and 304 that are substantially the same as the side surfaces 218, 220, 222, 224, and 226 respectively, except that the piston 290 defines an elongate dovetail projection 306 extending along the surface 296, and an elongate dovetail projection 308 extending along the surface 302.

Referring to FIGS. 16 and 19, the first rotor 288 is substantially the same as the first rotor 104 (shown in FIGS. 1, 3, 4, and 12 to 15) and has an axial surface 310 that is substantially the same as the axial surface 170, except that the first rotor 288 defines an elongate dovetail recess shown generally at 312 and extending along the surface 310. The recess 312 is sized to receive the projection 306 such that when the projection 306 is received in the recess 312, the projection 306 can slide along the recess 312 with the surface 296 held against the surface 310. Accordingly, when the projection 306 is received in the recess 312, the projection 306 and the recess 312 cooperate to prevent rotation of the piston 290 relative to the first rotor 288. In other words, the projection 306 and the recess 312 permit the piston 290 to slide relative to the first rotor 288 and maintain a relative orientation of the piston 290 relative to the first rotor 288 by maintaining the surface 296 generally parallel to the surface 310.

Referring to FIGS. 16 and 20, the second rotor 292 is substantially the same as the second rotor 110 (shown in FIGS. 1, 8, 9, and 12 to 15) and has a generally planar axial surface 314 that is substantially the same as the generally planar axial surface 250, except that the second rotor 292 defines an elongate dovetail recess shown generally at 316 and extending along the surface 314. The recess 316 is sized to receive the projection 308 such that when the projection 308 is received in the recess 316, the projection 308 can slide along the recess 316 with the surface 302 held against the surface 314. Accordingly, the piston 290 may be coupled to the second rotor 292 at the recess 316, so the portion of the second rotor 292 defining the recess 316 is a coupling portion of the second rotor 292. Further, when the projection 308 is received in the recess 316, the projection 308 and the recess 316 cooperate to prevent rotation of the piston 290 relative to the second rotor 292. In other words, the projection 308 and the recess 316 permit the piston 290 to slide relative to the second rotor 292 and maintain a relative orientation of the piston 290 relative to the second rotor 292 by maintaining the surface 302 generally parallel to the surface 314. Therefore, the apparatus 284 may function as a fluid pump in substantially the same way as the apparatus 100.

As another example, referring to FIG. 21, a piston machine apparatus according to another illustrative embodiment is shown generally at 318 and includes a first end body 320, a first rotor 322, a piston 324, a second rotor 326, and a second end body 328. The first end body 320 is substantially the same as the first end body 286 (shown in FIG. 16), and the second end body 328 is substantially the same as the second end body 294 (also shown in FIG. 16).

Referring to FIGS. 21 to 23, the piston 324 is substantially the same as the piston 108 (shown in FIGS. 1, 6, 7, and 12 to 15) and has side surfaces 330, 332, 334, 336, and 338 that are substantially the same as the side surfaces 218, 220, 222, 224, and 226 respectively, except that the piston 324 does not define any projections and instead defines a cavity shown generally at 340 and open to an opening in the surface 334.

Referring to FIGS. 21 and 22, the first rotor 322 is substantially the same as the first rotor 104 (shown in FIGS. 1, 3, 4, and 12 to 15) with axial surfaces 342 and 344 that are substantially the same as the axial surfaces 166 and 170 respectively and with a disc portion 346 that is substantially the same as the disc portion 178, except that the first rotor 322 defines a projection 348 projecting from the surface 344 and spaced apart from the disc portion 346. The projection 348 has an end surface 350 facing the surface 342 and generally parallel to and spaced apart from the surface 342, and the cavity 340 is sized to receive the projection 348 with the surface 350 received in the cavity 340 and holding the surface 330 against the surface 342 while permitting the piston 324 to slide along the surface 342 in a direction generally parallel to the surface 342. Accordingly, when the projection 348 is received in the cavity 340, the projection 348 and the cavity 340 cooperate to prevent rotation of the piston 324 relative to the first rotor 322. In other words, the projection 348 and the cavity 340 permit the piston 324 to slide relative to the first rotor 322 and maintain a relative orientation of the piston 324 relative to the first rotor 322 by maintaining the surface 330 generally parallel to the surface 342.

Referring to FIGS. 21 and 23, the second rotor 326 is substantially the same as the second rotor 110 (shown in FIGS. 1, 8, 9, and 12 to 15) with a generally planar axial surface 352 that is substantially the same as the generally planar axial surface 250 and with a generally cylindrical portion 354 that is substantially the same as the generally cylindrical portion 234, except that the second rotor 326 defines a projection 356 spaced apart from the generally cylindrical portion 354. The projection 356 has a surface 358 facing the surface 352 and generally parallel to and spaced apart from the surface 352, and the cavity 340 is sized to receive the projection 348 with the surface 358 received in the cavity 340 and holding the surface 336 against the surface 352 while permitting the piston 324 to slide along the surface 352 in a direction generally parallel to the surface 352. Accordingly, the piston 324 may be coupled to the second rotor 326 at the projection 356, so the projection 356 is a coupling portion of the second rotor 326. Further, when the projection 356 is received in the cavity 340, the projection 356 and the cavity 340 cooperate to prevent rotation of the piston 324 relative to the second rotor 326. In other words, the projection 356 and the cavity 340 permit the piston 324 to slide relative to the second rotor 326 and maintain a relative orientation of the piston 324 relative to the second rotor 326 by maintaining the surface 336 generally parallel to the surface 352. Therefore, the apparatus 318 may function as a fluid pump in substantially the same way as the apparatus 100 or the apparatus 284.

As another example, referring to FIGS. 24 and 25, a piston machine apparatus according to another illustrative embodiment is shown generally at 360 and includes a first rotor 362, a piston 364, and a second rotor 366. The apparatus 360 also includes end bodies (not shown) such as those described above. The piston 364 defines generally cylindrical recesses shown generally at 368 and 370. Further, the first rotor 362 defines a generally cylindrical projection 372 sized to be received in the recess 368, and the second rotor 366 defines a generally cylindrical projection 374 sized to be received in the recess 370. Accordingly, the piston 364 may be coupled to the second rotor 366 at the projection 374, so the projection 374 is a coupling portion of the second rotor 366. When the projection 372 is received in the recess 368, the projection 372 and the recess 368 cooperate to prevent rotation of the piston 364 relative to the first rotor 362 and thus permit the piston 364 to slide relative to the first rotor 362 and maintain a relative orientation of the piston 364 relative to the first rotor 362. Further, when the projection 374 is received in the recess 370, the projection 374 and the recess 370 cooperate to prevent rotation of the piston 364 relative to the second rotor 366 and thus permit the piston 364 to slide relative to the second rotor 366 and maintain a relative orientation of the piston 364 relative to the second rotor 366. Otherwise, the apparatus 360 may function as a fluid pump in substantially the same way as the apparatus 100, the apparatus 284, or the apparatus 318.

As another example, referring to FIGS. 26 and 27, a piston machine apparatus according to another illustrative embodiment is shown generally at 376 and includes a first rotor 378, a piston 380, and a second rotor 382. The apparatus 376 also includes end bodies (not shown) such as those described above. The piston 380 defines elongate recesses shown generally at 384 and 386. Further, the first rotor 378 defines an elongate projection 388 sized to be received in the recess 384, and the second rotor 382 defines an elongate projection 390 sized to be received in the recess 386. Accordingly, the piston 380 may be coupled to the second rotor 382 at the projection 390, so the projection 390 is a coupling portion of the second rotor 382. When the projection 388 is received in the recess 384, the projection 388 and the recess 384 cooperate to prevent rotation of the piston 380 relative to the first rotor 378 and thus permit the piston 380 to slide relative to the first rotor 378 and maintain a relative orientation of the piston 380 relative to the first rotor 378. Further, when the projection 390 is received in the recess 386, the projection 390 and the recess 386 cooperate to prevent rotation of the piston 380 relative to the second rotor 382 and thus permit the piston 380 to slide relative to the second rotor 382 and maintain a relative orientation of the piston 380 relative to the second rotor 382. Otherwise, the apparatus 376 may function as a fluid pump in substantially the same way as the apparatus 100, the apparatus 284, the apparatus 318, or the apparatus 360.

Although the aforementioned illustrative embodiments include particular structures for coupling a piston to a first rotor and to a second rotor to allow the piston to slide relative to the first rotor and relative to the second rotor in response to rotation of the first rotor around a first axis of rotation and in response to rotation of the second rotor around a second axis of rotation, alternative embodiments may include various different structures, including combinations and variations of the aforementioned structures, and including structures that differ from the aforementioned structures.

As an example of another illustrative embodiment, referring to FIGS. 28 to 30, a piston machine apparatus is shown generally at 392 and includes a first end body 394, a first rotor 396, a piston 398, a second rotor 400, and a second end body 402. Like the first end body 286 (shown in FIG. 16), the first end body 394 is similar to the first end body 102 (shown in FIGS. 1 and 2) integrally formed with the intermediate body 106 (shown in FIGS. 1 and 5). As shown in FIG. 30, the first end body 394 has a generally annular inner surface 404 that is substantially the same as the generally annular inner surface 188 (shown in FIGS. 1 and 5). More particularly, the generally annular inner surface 404 defines a first recess shown generally at 406 and that is positioned in substantially the same location in the apparatus 392 as the first recess 190 (also shown in FIGS. 1 and 5) in the apparatus 100, and the generally annular inner surface 404 defines a second recess shown generally at 408 and that is positioned in substantially the same location in the apparatus 392 as the second recess 192 (also shown in FIGS. 1 and 5) in the apparatus 100. However, unlike the first end body 102, which (as indicated above) defines the through-opening 122 positioned to be in fluid communication with the first recess 190 and thus functioning as a fluid inlet, the first end body 394 defines a through-opening shown generally at 410 and positioned to be in fluid communication with the second recess 408, and the through-opening 410 is thus positioned to function as a fluid outlet.

The first rotor 396, the piston 398, and the second rotor 400 are substantially the same as the first rotor 322, the piston 324, and the second rotor 326 (shown in FIGS. 21 to 23) respectively, except that the second rotor 400 defines a recess shown generally at 412 and that is positioned differently from the recess 239 (shown in FIGS. 1, 8, 9, and 12) as shown in FIGS. 28 and 30.

The second end body 402 is substantially the same as the second end body 112 (shown in FIG. 1), which (as indicated above) defines the through-opening 270 positioned to be in fluid communication with the second recess 192 and thus functioning as a fluid outlet, except that the second end body 402 defines a through-opening shown generally at 414 and positioned to be in fluid communication with the first recess 406, and the through-opening 414 is thus positioned to function as a fluid inlet. However, as described above with respect to the recess 239, the second rotor 400 covers the through-opening 414 except when the second rotor 400 is rotationally positioned such that the recess 412 is positioned over the through-opening 414. Therefore, the through-opening 414 is positioned to be in fluid communication with the first recess 406 when the second rotor 400 is rotationally positioned such that the recess 412 is positioned over the through-opening 414. In other words, the second rotor 400 can control fluid flow through the through-opening 414 in response to rotation of the second rotor 400.

In summary, the apparatus 392 is similar to the apparatus 100, but the fluid inlet and the fluid outlet of the apparatus 392 are on opposite sides when compared to the apparatus 100, and the recess 412 is positioned differently from the recess 239. As such, the second rotor 400 controls fluid flow through the fluid inlet of the apparatus 392 instead of the fluid outlet as in the apparatus 100.

As another example, referring to FIGS. 31 to 33, a piston machine apparatus according to another illustrative embodiment is shown generally at 416 and includes a first end body 418, a first rotor 420, a piston 422, a second rotor 424, and a second end body 426. The apparatus 416 is similar to the apparatus 392 shown in FIGS. 28 to 30, except that the first end body 418 defines a through-opening shown generally at 428 and positioned to function as a fluid inlet, and a through-opening shown generally at 430 and positioned to function as a fluid outlet. Also, the first rotor 420 defines a peripheral recess shown generally at 432.

As shown in FIG. 33, the first end body 418 has a generally annular inner surface 434 that is substantially the same as the generally annular inner surface 188 (shown in FIGS. 1 and 5). More particularly, the surface 434 includes a first curved portion 436 similar to the first curved portion 194 (also shown in FIGS. 1 and 5), and a second curved portion 438 similar to the second curved portion 196 (also shown in FIGS. 1 and 5). The first curved portion 436 extends along an arc of a peripheral outer surface 440 of the first rotor 420, and the second curved portion 438 extends along an arc of a peripheral outer surface 442 of the second rotor 424. The first curved portion 436 thus curves along a smaller radius of curvature than the second curved portion 438. The through-opening 428 extends between the first curved portion 436 and the second curved portion 438, and is thus in fluid communication with a chamber defined by the apparatus 416 except when the second rotor 424 covers the through-opening 428. However, the through-opening 430 is spaced apart from the surface 434 but proximate the first curved portion 436, and is thus covered by the first rotor 420 except when the except when the first rotor 420 is rotationally positioned such that the recess 432 is positioned over the through-opening 430. Therefore, the first rotor 420 can control fluid flow through the through-opening 430 (and thus through the fluid outlet of the apparatus 416) in response to rotation of the first rotor 420.

As another example, referring to FIGS. 34 to 36, a piston machine apparatus according to another illustrative embodiment is shown generally at 444 and includes a first end body 446, a first rotor 448, a piston 450, a second rotor 452, and a second end body 454. The apparatus 444 is similar to the apparatus 416 shown in FIGS. 31 to 33, and the first end body 446 defines a through-opening shown generally at 456 and positioned to function as a fluid inlet, and a through-opening shown generally at 458 and positioned to function as a fluid outlet. Also, the first rotor 448 defines a peripheral recess shown generally at 460 that is positioned differently from the recess 420 (shown in FIGS. 31 and 33) as shown in FIGS. 34 and 36. As in the apparatus 416, the first end body 446 has a generally annular inner surface 462 that includes a first curved portion 464 and a second curved portion 466, the first curved portion 464 curving along a smaller radius of curvature than the second curved portion 466.

However, unlike the apparatus 416, the through-opening 458 (which is positioned to function as a fluid outlet) extends between the first curved portion 464 and the second curved portion 466, and is thus in fluid communication with a chamber defined by the apparatus 444 except when the second rotor 452 covers the through-opening 458, and the through-opening 456 (which is positioned to function as a fluid inlet) is spaced apart from the surface 462 but proximate the first curved portion 464, and is thus covered by the first rotor 448 except when the except when the first rotor 448 is rotationally positioned such that the recess 460 is positioned over the through-opening 456. Therefore, the first rotor 448 can control fluid flow through the through-opening 456 (and thus through the fluid inlet of the apparatus 444) in response to rotation of the first rotor 448.

Referring to FIG. 37, a piston machine apparatus according to another illustrative embodiment is shown generally at 468 and includes a first end body 470, a first rotor 472, a piston 474, a second rotor 476, an intermediate body 478, and a second end body 480.

Referring to FIGS. 37 and 38, the first end body 470 is generally cylindrical about an axis 482 and has an outer side shown generally at 484 and an inner side shown generally at 486 and opposite the outer side 484. On the outer side 484, the first end body 470 has an outer surface 488 that is generally circular around the axis 482. On the inner side 486, the first end body 470 has an inner surface 490 that is generally annular around the axis 482, a generally cylindrical projection 492 surrounded by the inner surface 490 and having an inner surface 494 that is generally annular around the axis 482, and a generally cylindrical projection 496 surrounded by the inner surface 494 and having an inner surface 498 that is generally circular around the axis 482. A through-opening shown generally at 500 extends between the outer surface 488 and the inner surface 498 of the first end body 470, and the through-opening 500 is generally cylindrical with a radius 502 about an axis 504 that is generally parallel to and spaced apart (or different) from the axis 482. Otherwise, the first end body 470 is generally rotationally symmetric around the axis 482. A generally annular surface 506 extends by a height 508 between the inner surface 490 and the inner surface 494 and has a radius 510 around the axis 482, and a generally annular surface 512 extends between the inner surface 494 and the inner surface 498 by a height 514 and has a radius 516 around the axis 482.

Still referring to FIGS. 37 and 38, the second end body 480 is substantially the same as the first end body 470 and has an outer side shown generally at 518, an inner side shown generally at 520 and opposite the outer side 518, an inner surface 522 that is substantially the same as the inner surface 490, an inner surface 524 that is substantially the same as the inner surface 494, an inner surface 526 that is substantially the same as the inner surface 498, a generally annular surface 528 that is substantially the same as the generally annular surface 506, a generally annular surface 530 that is substantially the same as the generally annular surface 512, and a through-opening shown generally at 532 that is substantially the same as the through-opening 500.

Referring to FIGS. 37 and 39, the first rotor 472 includes generally cylindrical shafts 534 and 536 extending along a common axis 538 and each having a radius 540 around the axis 538. The radius 540 is approximately equal to the radius 502 of the through-openings 500 and 532 (shown in FIGS. 37 and 38). Between the shafts 534 and 536, the first rotor 472 includes generally radial projections 542 and 544 extending generally radially away from the shafts 534 and 536 and generally opposite from each other. Each of the projections 542 and 544 has an axial length 546 along the axis 538, and the projections 542 and 544 terminate in end portions 548 and 550 respectively. Each of the end portions 548 and 550 has an axial length 552 along the axis 538, the axial length 552 being greater than the axial length 546. The end portions 548 and 550 have curved outer surfaces 554 and 556 respectively, which face away from the axis 538, and which curve around the axis 538 at a radius of curvature 558. The end portions 548 and 550 also have generally planar surfaces 560 and 562 respectively, which face towards the axis 538, and which are generally parallel to each other in planes that are generally parallel to the axis 538. Each of the generally planar surfaces 560 and 562 is spaced apart from the axis 538 by a distance 564, which is less than the radius of curvature 558, and which is generally constant. The projection 542 defines a recess shown generally at 566 and facing the generally planar surface 560, and the projection 544 defines a recess shown generally at 568 and facing the generally planar surface 562.

Referring to FIGS. 37, 40, and 41, the intermediate body 478 is generally annular and has an inner surface 570, an outer surface 572, and generally annular end surfaces 574 and 576 extending between the inner surface 570 and the outer surface 572. The outer surface 572 curves around an axis 578 with a radius of curvature 580. The inner surface 570 curves around the axis 578 with a radius of curvature 582, which is less than the radius of curvature 580, except that the inner surface 570 also defines a recessed portion shown generally at 584, which extends an axial length 586 and curves around an axis 588 with a radius of curvature 590, which is less than the radius of curvature 582. The radius of curvature 582 is approximately equal to the radius 510 (shown in FIG. 38), and the axial length 586 is approximately equal to the axial length 552 (shown in FIG. 39). The axis 588 is generally parallel to and spaced apart (or different) from the axis 578, and the separation distance between the axes 578 and 588 is approximately equal to the separation distance between the axes 482 and 504 (shown in FIGS. 37 and 38). The radius of curvature 590 is approximately equal to the radius of curvature 558 (shown in FIG. 39). The intermediate body 478 also defines through-openings shown generally at 592 and 594 extending between the inner surface 570 and the outer surface 572 on alternate peripheral sides of the recessed portion 584.

Referring to FIGS. 37, 42, and 43, the second rotor 476 includes generally planar, generally parallel, and spaced apart generally annular portions 596 and 598 defining respective generally circular through-openings shown generally at 600 and 602 respectively. The generally annular portions 596 and 598 have radially outer surfaces that curve at a radius of curvature 604 around an axis 606, and each of the through-openings 600 and 602 has a radius 608 around the axis 606. The radius of curvature 604 is approximately equal to the radius 510 (shown in FIG. 38) and to the radius of curvature 582 (shown in FIGS. 40 and 41), and the radius 608 is approximately equal to the radius 516 (also shown in FIG. 38). Also, each of the generally annular portions 596 and 598 has an axial thickness 610 that is approximately equal to the height 514 (shown in FIG. 38), and the generally annular portions 596 and 598 are spaced apart from each other by an axial distance 612 that is approximately equal to the axial length 552 (shown in FIG. 39).

The second rotor 476 also includes connectors 614 and 616 extending generally parallel to the axis 606 between and connecting the generally annular portions 596 and 598. The connectors 614 and 616 have curved outer surfaces 618 and 620 respectively, which face away from the axis 606 and, like the radially outer surfaces of the generally annular portions 596 and 598, curve around the axis 606 at the radius of curvature 604. The connectors 614 and 616 also have generally planar surfaces 622 and 624 respectively, which face towards the axis 606, and which are generally parallel to each other in planes that are generally parallel to the axis 606. Each of the generally planar surfaces 622 and 624 is spaced apart from the axis 606 by a distance 626, which is less than the radius of curvature 604 and greater than the radius 608, and which is generally constant. The second rotor 476 defines a cavity shown generally at 628 between the generally annular portions 596 and 598 and between the generally planar surfaces 622 and 624. The cavity 628 is open at the through-openings 600 and 602 and is open at laterally opposite spaces shown generally at 630 and 632 between the generally planar surfaces 622 and 624.

Referring to FIGS. 37, 44, 45, and 46, the piston 474 includes generally planar, generally parallel, and spaced apart portions 634 and 636 defining respective elongate through-openings shown generally at 638 and 640 respectively. The through-openings 638 and 640 are wide enough to receive the shafts 534 and 536 respectively, and are long enough to permit the shafts 534 and 536 to move transversely in the through-openings 638 and 640 respectively relative to the piston 474 as described below. Each of the portions 634 and 636 has a thickness 642 that is approximately half of the difference between the axial length 546 and the axial length 552 (both shown in FIG. 39), and the portions 634 and 636 are spaced apart from each other by a distance 644 that is approximately equal to the axial length 546 (shown in FIG. 39).

The piston 474 also includes connectors 646 and 648 extending between and connecting the portions 634 and 636. The connectors 646 and 648 define respective generally planar outer surfaces 650 and 652 that are generally parallel to each other and spaced apart from each other by a separation distance 654. The separation distance 654 is approximately double the distance 626 (shown in FIGS. 42 and 43). The connector 646 also defines curved lateral outer surfaces 656 and 658 extending between the generally planar outer surface 650 and outer surfaces of the portions 634 and 636 respectively, and the outer surfaces 650, 656, and 658 are configured to contact closely and slide along inner surfaces of the connector 614 (shown in FIGS. 37 and 42) when the piston 474 is received in the cavity 628 with the generally planar outer surface 650 closely contacting the generally planar surface 622 (shown in FIGS. 42 and 43) and with the generally planar outer surface 652 closely contacting the generally planar surface 624 (shown in FIGS. 42 and 43). Likewise, the connector 646 also defines curved lateral outer surfaces 660 and 662 extending between the generally planar outer surface 652 and the outer surfaces of the portions 634 and 636 respectively, and the outer surfaces 652, 660, and 662 are configured to contact closely and slide along inner surfaces of the connector 616 (shown in FIGS. 37 and 42) when the piston 474 is received in the cavity 628 with the generally planar outer surface 650 closely contacting the generally planar surface 622 (shown in FIGS. 42 and 43) and with the generally planar outer surface 652 closely contacting the generally planar surface 624 (shown in FIGS. 42 and 43).

The portions 634 and 636 and the connector 646 collectively define a generally planar outer surface 664 of the piston 474 between the generally planar outer surfaces 650 and 652, and the portions 634 and 636 and the connector 648 collectively define a generally planar outer surface 666 of the piston 474 between the generally planar outer surfaces 650 and 652 and opposite the generally planar outer surface 664. The generally planar outer surfaces 664 and 666 are generally parallel to each other, are generally parallel to a transverse direction in which the through-openings 638 and 640 are elongate, and are spaced apart from each other by a distance 668, which is approximately double the distance 564 (shown in FIG. 39). The generally planar outer surfaces 664 and 666 are generally perpendicular to both of the generally planar outer surfaces 650 and 652. Further, the connector 646 defines a curved outer surface 667 extending between the generally planar outer surface 650 and the generally planar outer surface 664, and the connector 648 defines a curved outer surface 669 extending between the generally planar outer surface 652 and the generally planar outer surface 666.

Referring to FIGS. 37, 47, 48, and 49, the apparatus 468 may be assembled by positioning the projections 542 and 544 (shown in FIG. 39) of the first rotor 472 between the portions 634 and 636 of the piston 474, with the shaft 534 passing through the through-opening 638 and the shaft 536 passing through the through-opening 640. Although the first rotor 472 and the piston 474 are illustrated as unitary bodies, one or both of the first rotor 472 and the piston 474 may be assembled from multiple bodies to permit the apparatus 468 to be assembled as described herein. For example, the piston 474 may be assembled from two halves.

As indicated above, the generally planar outer surfaces 664 and 666 of the piston 474 spaced apart from each other by the distance 668 (shown in FIGS. 44 and 46), which is approximately double the distance 564 (shown in FIG. 39), so the generally planar outer surfaces 664 and 666 of the piston 474 are spaced apart from each other by approximately the same distance that separates the generally planar surfaces 560 and 562 of the first rotor 472. Therefore, when the projections 542 and 544 of the first rotor 472 are between the portions 634 and 636 of the piston 474 as shown in FIG. 48, the generally planar surfaces 560 and 562 of the first rotor 472 closely contact the generally planar outer surfaces 664 and 666 respectively of the piston 474, and the end portions 548 and 550 of the first rotor 472, which have the generally planar surfaces 560 and 562 respectively, couple the piston 474 to the first rotor 472 with the piston 474 slidable relative to the first rotor 472 in a direction that is generally parallel to the generally planar surfaces 560, 562, 664, and 666. As such, one or both of the end portions 548 and 550 of the first rotor 472 is a first coupling portion of the first rotor 472 that is coupled to the piston 474, and the piston 474 can slide along a first linear path relative to the first coupling portion, namely a path generally parallel to the generally planar surfaces 560, 562, 664, and 666 (which is generally perpendicular to a radius perpendicular to the axis 538) and generally parallel to a plane of rotation of the first rotor 472. Further, the end portions 548 and 550 of the first rotor 472, which have the generally planar surfaces 560 and 562 respectively, maintain a relative orientation of the piston 474 relative to the first rotor 472, namely an orientation in which the generally planar surfaces 560 and 562 of the first rotor 472 are generally parallel to the generally planar outer surfaces 664 and 666 respectively of the piston 474, even as the first rotor 472 rotates around the axis 538 and as the piston 474 slides relative to the first rotor 472.

Also, as indicated above, the generally planar surfaces 560 and 562 of the first rotor 472 are generally parallel to each other and the generally planar outer surfaces 664 and 666 of the piston 474 are generally parallel to each other and generally parallel to the transverse direction in which the through-openings 638 and 640 are elongate, so when the generally planar surfaces 560 and 562 of the first rotor 472 closely contact the generally planar outer surfaces 664 and 666 respectively of the piston 474 as shown in FIG. 48, the piston 474 can slide relative to the first rotor 472 as the generally planar surfaces 560 and 562 of the first rotor 472 slide relative to the generally planar outer surfaces 664 and 666 respectively, and as the shafts 534 and 536 slide with the first rotor 472 relative to the piston 474 in the through-openings 638 and 640 respectively. As shown in FIG. 49, the projection 542 is shaped to abut the connector 646, receiving a portion of the connector 646 in the recess 566, when the connector 646 slides relative to the first rotor 472 in a direction towards the projection 542, and the projection 544 is shaped to abut the connector 648, receiving a portion of the connector 648 in the recess 568, when the connector 648 slides relative to the first rotor 472 in a direction towards the projection 544.

Still referring to FIGS. 37, 47, 48, and 49, the apparatus 468 may be assembled further by positioning the first rotor 472 and the piston 474, assembled as described above, in the cavity 628 of the second rotor 476 with the shaft 534 passing through the through-opening 600, with the shaft 536 passing through the through-opening 602 (shown in FIG. 42), with the generally planar outer surface 650 of the piston 474 closely contacting the generally planar surface 622 of the second rotor 476 such that the outer surfaces 650, 656, and 658 of the piston 474 closely contact and are slidable along the inner surfaces of the connector 614 (shown in FIGS. 37 and 42) in a direction generally parallel to the generally planar surfaces 622 and 650, and with the generally planar outer surface 652 of the piston 474 closely contacting the generally planar surface 624 of the second rotor 476 such that the outer surfaces 652, 660, and 662 (shown in FIG. 45) closely contact and are slidable along the inner surfaces of the connector 616 (shown in FIGS. 37 and 42) in a direction generally parallel to the generally planar surfaces 624 and 652. Again, although the first rotor 472, the piston 474, and the second rotor 476 are illustrated as unitary bodies, one or more of the first rotor 472, the piston 474, and the second rotor 476 may be assembled from multiple bodies to permit the apparatus 468 to be assembled as described herein.

The apparatus 468 may be assembled further by positioning the first rotor 472, the piston 474, and the second rotor 476, assembled as described above, in the intermediate body 478 such that the axes 578 and 606 are generally collinear and the curved outer surfaces 618 and 620 (shown in FIGS. 42 and 43) of the second rotor 476, along with the radially outer surfaces of the generally annular portions 596 and 598 of the second rotor 476, closely contact and slide against the inner surface 570 (outside the recessed portion 584) of the intermediate body 478 as the second rotor 476 rotates in the intermediate body 478 around the axis 606.

The apparatus 468 may be assembled further by attaching the first end body 470 to the intermediate body 478 by one or more fasteners (such as bolts, screws, or rivets, for example), by complementary threads (not shown), by welding, by soldering, or by adhesive, for example, with the first rotor 472, the piston 474, and the second rotor 476 in the intermediate body 478 as described above, with the shaft 534 passing through the through-opening 500, with the inner surface 490 of the first end body 470 against the intermediate body 478, with the axes 482, 578, and 606 generally collinear, and with the axes 504, 538, and 588 generally collinear. As indicated above, the axis 504 is generally parallel to and spaced apart (or different) from the axis 482, and when the apparatus 468 is assembled as described above, the axes 504 and 588 are generally collinear, and the axes 482, 578, and 606 are generally collinear. Therefore, when the apparatus 468 is assembled as described above, the axis 538 is generally parallel to and spaced apart (or different) from the axis 606.

Also, as indicated above, the radius 540 (shown in FIG. 39) of the shafts 534 and 536 is approximately equal to the radius 502 (shown in FIG. 38) of the through-openings 500 and 532, so the shafts 534 and 536 closely contact inner surfaces of the through-openings 500 and 532 respectively when the apparatus 468 is assembled as shown. Further, as indicated above, the radius of curvature 558 of the curved outer surfaces 554 and 556 (shown in FIG. 39) of the first rotor 472 is approximately equal to the radius of curvature 590 of the portion of the inner surface 570 in the recessed portion 584 (shown in FIGS. 40 and 41) of the intermediate body 478, so when the axes 538 and 588 are generally collinear, some or all of the curved outer surface 554, or some or all of the curved outer surface 556, may closely contact the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478, depending on a rotational position of the first rotor 472 around the axis 538.

The apparatus 468 may be assembled further by attaching the second end body 480 to the intermediate body 478 by one or more fasteners (such as bolts, screws, or rivets, for example), by complementary threads (not shown), by welding, by soldering, or by adhesive, for example, with the first rotor 472, the piston 474, and the second rotor 476 in the intermediate body 478 as described above, with the shaft 536 passing through the through-opening 532, and with the inner surface 522 of the second end body 480 against the intermediate body 478. When the apparatus 468 is assembled as described above, the first end body 470, the intermediate body 478, and the second end body 480 collectively form a housing of the apparatus 468 and the first rotor 472, the piston 474, and the second rotor 476 are in the housing.

As shown in FIGS. 48 and 49, when the apparatus 468 is assembled as described above, the close contact between the shafts 534 and 536 and the inner surfaces of the through-openings 500 and 532, and the close contact between the outer surfaces of the second rotor 476 and the inner surface 570 of the intermediate body 478, define fluid barriers that enclose the cavity 628 (shown in FIGS. 37 and 42) of the second rotor 476.

Further, as indicated above and as shown in FIGS. 48 and 49, when the apparatus 468 is assembled as described above, the generally planar surface 560 of the end portion 548 of the first rotor 472 closely contacts the generally planar outer surface 664 of the piston 474, and the generally planar surface 562 of the end portion 550 of the first rotor 472 closely contacts the generally planar outer surface 666 of the piston 474. Therefore, when the apparatus 468 is assembled as described above, a portion of the generally planar outer surface 664 that is on the connector 646 of the piston 474 defines a fluid barrier 670 between the connector 646 and the end portion 548 of the first rotor 472, and a portion of the generally planar outer surface 666 that is on the connector 648 of the piston 474 defines a fluid barrier 672 between the connector 648 and the end portion 550 of the first rotor 472.

Further, as indicated above, when the apparatus 468 is assembled as described above, the outer surfaces 650, 656, and 658 (shown in FIGS. 37 and 45) of the piston 474 closely contact the inner surfaces of the connector 614 (shown in FIGS. 37 and 42), and the outer surfaces 652, 660, and 662 (shown in FIG. 45) closely contact the inner surfaces of the connector 616 (shown in FIGS. 37 and 42). Therefore, when the apparatus 468 is assembled as described above, the outer surfaces 650, 656, and 658 (shown in FIGS. 37 and 45) of the piston 474 and the inner surfaces of the connector 614 define a fluid barrier 674 between the connector 646 of the piston 474 and the connector 614 of the second rotor 476, and the outer surfaces 652, 660, and 662 of the piston 474 and the inner surfaces of the connector 616 define a fluid barrier 676 between the connector 648 of the piston 474 and the connector 616 of the second rotor 476. Therefore, when the when the apparatus 468 is assembled as described above, the connectors 614 and 616 of the second rotor 476, which have the generally planar surfaces 622 and 624 respectively, couple the piston 474 to the second rotor 476 with the piston 474 slidable relative to the second rotor 476 in a direction that is generally parallel to the generally planar surfaces 622, 624, 650, and 652. As such, one or both of the connectors 614 and 616 of the second rotor 476 is a second coupling portion of the second rotor 476 that is coupled to the piston 474, and the piston 474 can slide along a second linear path relative to the second coupling portion, namely a path generally parallel to the generally planar surfaces 622, 624, 650, and 652 (which is generally perpendicular to a radius perpendicular to the axis 606) and generally parallel to a plane of rotation of the second rotor 476. Further, the connectors 614 and 616 of the second rotor 476, which have the generally planar surfaces 622 and 624 respectively, maintain a relative orientation of the piston 474 relative to the second rotor 476, namely an orientation in which the generally planar surfaces 622 and 624 of the second rotor 476 are generally parallel to the generally planar outer surfaces 650 and 652 respectively of the piston 474, even as the second rotor 476 rotates around the axis 606 and as the piston 474 slides relative to the second rotor 476.

Referring to FIGS. 49 and 50, a torque may be applied to one or both of the shafts 534 and 536 (shown in FIGS. 37 and 39) of the first rotor 472 to cause the first rotor 472 to rotate around the axis 538 (which, as indicated above, is generally collinear with the axes 504 and 588) in a direction of rotation shown by the arrow 678. Additionally or alternatively, a torque may be applied to the second rotor 476, for example by one or more gears (not shown) in contact with gear teeth (not shown) the second rotor 476, to cause the second rotor 476 to rotate around the axis 606 (which, as indicated above, is generally collinear with the axes 482 and 578) in the direction of rotation shown by the arrow 678.

As indicated above, depending on a rotational position of the first rotor 472 around the axis 538, some or all of the curved outer surface 554 of the end portion 548 of the first rotor 472, or some or all of the curved outer surface 556 of the end portion 550 of the first rotor 472, may closely contact the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478. Therefore, when the first rotor 472 has a rotational position around the axis 538 in which the curved outer surface 554 of the first rotor 472 closely contacts the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478, as shown in FIGS. 49 and 50, then the curved outer surface 554 of the first rotor 472 and the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478 define a fluid barrier 680 between the end portion 548 (which has the curved outer surface 554) of the first rotor 472 and the recessed portion 584 of the intermediate body 478.

Further, as indicated above, when the apparatus 468 is assembled as described above, the curved outer surfaces 618 and 620 of the second rotor 476 closely contact and slide against the inner surface 570 (outside the recessed portion 584) of the intermediate body 478. Therefore, when the second rotor 476 has a rotational position around the axis 606 in which the curved outer surface 618 of the second rotor 476 closely contacts the inner surface 570 (outside the recessed portion 584) of the intermediate body 478, as shown in FIGS. 49 and 50, then the curved outer surface 618 of the second rotor 476 and the inner surface 570 (outside the recessed portion 584) of the intermediate body 478 define a fluid barrier 682 between the connector 614 (which has the curved outer surface 618) of the second rotor 476 and the intermediate body 478 outside the recessed portion 584.

As indicated above, the first rotor 472 maintains a relative orientation of the piston 474 relative to the first rotor 472, and the second rotor 476 maintains a relative orientation of the piston 474 relative to the second rotor 476. Therefore, rotation of the first rotor 472 around the axis 538 causes the first rotor 472 to transfer a torque to the piston 474 and causes the piston 474 to transfer a torque to the second rotor 476 to cause rotation of the second rotor 476 around the axis 606, and rotation of the second rotor 476 around the axis 606 causes the second rotor 476 to transfer a torque the piston 474 and causes the piston 474 to transfer a torque to the first rotor 472 to cause rotation of the first rotor 472 around the axis 538.

Therefore, by applying a torque in the direction of rotation shown by the arrow 678 to one or more of the shaft 534, the shaft 536, and the second rotor 476, the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIGS. 48 and 49 to the positions shown in FIG. 50. As the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIGS. 48 and 49 to the position shown in FIG. 50, a chamber shown generally at 684 is defined between the fluid barrier 670 (which, as indicated above, is between the end portion 548 of the first rotor 472 and the connector 646 of the piston 474), the fluid barrier 674 (which, as indicated above, is between the connector 646 of the piston 474 and the connector 614 of the second rotor 476), the fluid barrier 680 (which, as indicated above, is between the end portion 548 of the first rotor 472 and the recessed portion 584 of the intermediate body 478), and the fluid barrier 682 (which, as indicated above, is between the connector 614 of the second rotor 476 and the intermediate body 478 outside the recessed portion 584), and the chamber 684 is in fluid communication with the through-opening 592 in the intermediate body 478. In other words, the fluid barriers 670, 674, 680, and 682 define a continuous fluid barrier from a location where the curved outer surface 554 of the first rotor 472 closely contacts the recessed portion 584 of the intermediate body 478 to a location where the curved outer surface 618 of the second rotor 476 closely contacts the intermediate body 478, and that continuous fluid barrier defines the chamber 684 when the chamber 684 is in fluid communication with the through-opening 592 in the intermediate body 478.

The chamber 684 is defined by surfaces including the curved outer surface 554 of the first rotor 472, the generally planar outer surface 664 and the curved outer surface 667 of the piston 474, and the generally planar surface 622 of the second rotor 476. The curved outer surface 554, the generally planar outer surface 664, the curved outer surface 667, and the generally planar surface 622 all intersect a common plane (for example, a plane including the section line XLIX-XLIX in FIGS. 47 and 48) that is through the chamber 684 and that is perpendicular to the axes 538 and 606. Therefore, each of the first rotor 472, the piston 474, and the second rotor 476 has at least one surface that defines the chamber 684 in various positions, and that intersects the common plane that is through the chamber 684 and that is perpendicular to the axes 538 and 606. Also, varying the volume of the chamber 684 may involve moving at least one surface of the first rotor 472 (namely, the curved outer surface 554), at least one surface of the piston 474 (namely, the generally planar outer surface 664 and the curved outer surface 667), and at least one surface of the second rotor 476 (namely, the generally planar surface 622) that define the chamber 684 and that also intersect the common plane that is through the chamber 684 and that is perpendicular to the axes 538 and 606.

By applying the torque in the direction of rotation shown by the arrow 678, the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 50 to the positions shown in FIG. 51. As shown in FIGS. 49, 50, and 51, the fluid barrier 674 is a separation distance 686 from the axis 538. However, as indicated above, the fluid barrier 674 is defined by the connector 614 of the second rotor 476, which rotates around the axis 606, which is generally parallel to and spaced apart from the axis 538. Therefore, rotation of the second rotor 476 around the axis 606 varies a distance between the connector 614 and the axis 538, and more generally, the separation distance 686 varies in response to rotation of the first rotor 472 around the axis 538 and in response to rotation of the second rotor 476 around the axis 606. Also, because rotation of the second rotor 476 around the axis 606 causes the separation distance 686 to vary, because the first rotor 472 rotates around the axis 538, which is generally parallel to and spaced apart from the axis 606, and because the first rotor 472 maintains a relative orientation of the piston 474 relative to the first rotor 472, rotation of the second rotor 476 around the axis 606 causes the piston 474 to slide along the first linear path, namely the path generally parallel to the generally planar surfaces 560, 562, 664, and 666 and generally parallel to a plane of rotation of the first rotor 472.

More particularly, as the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 49 to the positions shown in FIG. 50, and from the positions shown in FIG. 50 to the positions shown in FIG. 51, the rotation of the second rotor 476 around the axis 606 causes the connector 614 (which, as indicated above, is a second coupling portion, the connector 616 being a third coupling portion of the second rotor 476 opposite and spaced apart from the second coupling portion and also coupled to the piston 474) to revolve around the end portions 548 and 550 (which, as indicated above, are a first coupling portion), the separation distance 686 increases, and the fluid barrier 674 moves away from the through-opening 592.

As indicated above, the fluid barriers 670, 674, 680, and 682 define a continuous fluid barrier, and as the first rotor 472, the piston 474, and the second rotor 476 as described herein, that continuous fluid barrier is varied to vary a volume of the chamber 684. More particularly, as the separation distance 686 increases, and as the fluid barrier 674 moves away from the through-opening 592, the chamber 684 remains in fluid communication with the through-opening 592 in the intermediate body 478 and the volume of the chamber 684 increases. In other words, expanding the chamber 684 involves revolving the second coupling portion (namely, the connector 614) of the second rotor 476 around the axis 606 in the direction of the arrow 678 and in a path around the first coupling portion (namely, one or both of the end portions 548 and 550 of the first rotor 472) away from the through-opening 592.

As indicated above, rotation of the second rotor 476 around the axis 606 causes the piston 474 to slide along the first linear path, in which the generally planar surfaces 560 and 562 of the first rotor 472 are generally parallel to the generally planar outer surfaces 664 and 666 respectively of the piston 474. As also indicated above, each of the generally planar surfaces 560 and 562 is spaced apart from the axis 538 by the distance 564, which is generally constant, and each of the generally planar surfaces 622 and 624 of the second rotor 476 is spaced apart from the axis 606 by the distance 626, which is also generally constant. Therefore, because the second rotor 476 rotates around the axis 606, which is generally parallel to and spaced apart from the axis 538, planes including the generally planar outer surfaces 664 and 666 of the piston 474 intersect planes including the generally planar surfaces 622 and 624 at points that vary relative to the second rotor 476 in response to rotation of the second rotor 476 around the axis 606. As indicated above, when the apparatus 468 is assembled as described above, the generally planar outer surfaces 650 and 652 of the piston 474 closely contact and are slidable along the generally planar surfaces 622 and 650 in a direction generally parallel to the generally planar surfaces 622 and 650. Therefore, rotation of the second rotor 476 around the axis 606 causes the piston 474 to slide along the second linear path, namely the path generally parallel to the generally planar surfaces 622, 624, 650, and 652 and generally parallel to a plane of rotation of the second rotor 476.

By applying the torque in the direction of rotation shown by the arrow 678, the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 51 to the positions shown in FIG. 52. As indicated above, when the apparatus 468 is assembled as described above, the curved outer surfaces 618 and 620 of the second rotor 476 closely contact and slide against the inner surface 570 (outside the recessed portion 584) of the intermediate body 478. Therefore, when the second rotor 476 has a rotational position around the axis 606 in which the curved outer surface 620 of the second rotor 476 closely contacts the inner surface 570 (outside the recessed portion 584) of the intermediate body 478, as shown in FIG. 52, then the curved outer surface 620 of the second rotor 476 and the inner surface 570 (outside the recessed portion 584) of the intermediate body 478 define a fluid barrier 688 between the connector 616 (which has the curved outer surface 620) of the second rotor 476 and the intermediate body 478 outside the recessed portion 584. As shown in FIG. 52, when the first rotor 472, the piston 474, and the second rotor 476 are in the positions shown in FIG. 51, the connector 616 (which defines the fluid barrier 688) fluidly separates the chamber 684 from the through-opening 592, which may thereby prevent fluid that was drawn into the chamber 684 from the through-opening 592 from flowing back out from the chamber 684 through the through-opening 592. In other words, the connector 616 (and thus the second rotor 476) can control fluid flow through the through-opening 592 in response to rotation of the second rotor 476 around the axis 606. Further, as indicated above, rotation of the second rotor 476 around the axis 606 may be in response to rotation of the first rotor 472 around the axis 538, so rotation of the first rotor 472 around the axis 538 may also control fluid flow through the through-opening 592.

By applying the torque in the direction of rotation shown by the arrow 678, the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 52 to the positions shown in FIG. 53. As indicated above, depending on a rotational position of the first rotor 472 around the axis 538, some or all of the curved outer surface 554 of the end portion 548 of the first rotor 472, or some or all of the curved outer surface 556 of the end portion 550 of the first rotor 472, may closely contact the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478. Therefore, when the first rotor 472 has a rotational position around the axis 538 in which the curved outer surface 556 of the first rotor 472 closely contacts the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478, as shown in FIG. 53, then the curved outer surface 556 of the first rotor 472 and the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478 define a fluid barrier 690 between the end portion 550 (which has the curved outer surface 556) of the first rotor 472 and the recessed portion 584 of the intermediate body 478.

In FIG. 53, the connector 616 of the second rotor 476 has rotated around the axis 606 past the through-opening 592 in the intermediate body 478, which creates the fluid barrier 688 (which, as indicated above, is between the connector 614 of the second rotor 476 and the intermediate body 478 outside the recessed portion 584), and which causes a chamber shown generally at 692 to be in fluid communication with the through-opening 592, and to be defined between the fluid barrier 672 (which, as indicated above, is between the end portion 550 of the first rotor 472 and the connector 648 of the piston 474), the fluid barrier 676 (which, as indicated above, is between the connector 648 of the piston 474 and the connector 616 of the second rotor 476), the fluid barrier 688, and the fluid barrier 690 (which, as indicated above, is between the end portion 550 of the first rotor 472 and the recessed portion 584 of the intermediate body 478). The chamber 692 is defined by surfaces and fluid barriers that correspond to surfaces and fluid barriers that define the chamber 684, but on an opposite side of the apparatus 468. Therefore, the chamber 692 moves, expands, and contracts in substantially the same as the chamber 684 as described herein, but on an opposite side of the apparatus 468. The chamber 692 is different from the chamber 684, and as shown in FIGS. 53 and 54 for example, applying the torque in the direction of rotation shown by the arrow 678 causes the chamber 692 to expand while causing the chamber 684 to contract.

By applying the torque in the direction of rotation shown by the arrow 678, the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 53 to the positions shown in FIG. 54, then to the positions shown in FIG. 55, and then to the positions shown in FIG. 56. In FIG. 54, the connector 614 of the second rotor 476 has rotated around the axis 606 past the through-opening 594, which removes the fluid barrier 682 and causes the chamber 684 to be in fluid communication with the through-opening 594 in the positions shown in FIGS. 54, 55, and 56. In other words, the connector 614 (and thus the second rotor 476) can control fluid flow through the through-opening 594 in response to rotation of the second rotor 476 around the axis 606. Further, as indicated above, rotation of the second rotor 476 around the axis 606 may be in response to rotation of the first rotor 472 around the axis 538, so rotation of the first rotor 472 around the axis 538 may also control fluid flow through the through-opening 594.

In FIGS. 55 and 56, the first rotor 472 has a rotational position around the axis 538 in which the curved outer surface 554 of the first rotor 472 closely contacts the portion of the inner surface 570 in the recessed portion 584 of the intermediate body 478, thereby defining again the fluid barrier 680 between the end portion 548 (which has the curved outer surface 554) of the first rotor 472 and the recessed portion 584 of the intermediate body 478. Therefore, in FIGS. 55 and 56, the fluid barriers 672, 676, 680, and 688 define a continuous fluid barrier from a location where the curved outer surface 554 of the first rotor 472 closely contacts the recessed portion 584 of the intermediate body 478 to a location where the curved outer surface 620 of the second rotor 476 closely contacts the intermediate body 478, and that continuous fluid barrier defines the chamber 684 when the chamber 684 is in fluid communication with the through-opening 594 in the intermediate body 478. As the first rotor 472, the piston 474, and the second rotor 476 as described herein, that continuous fluid barrier moves to vary a volume of the chamber 684.

More particularly, the fluid barrier 676 is a separation distance 694 from the axis 538, and as the first rotor 472, the piston 474, and the second rotor 476 move from the positions shown in FIG. 53 to the positions shown in FIG. 54, from the positions shown in FIG. 54 to the positions shown in FIG. 55, and from the positions shown in FIG. 55 to the positions shown in FIG. 56, the rotation of the second rotor 476 around the axis 606 causes the connector 616 (which, as indicated above, is a second coupling portion, the connector 614 being a third coupling portion of the second rotor 476 opposite and spaced apart from the second coupling portion and also coupled to the piston 474) to revolve around the end portions 548 and 550 (which, as indicated above, are a first coupling portion), the separation distance 694 decreases, and the fluid barrier 676 moves towards the through-opening 594. More generally, the separation distance 694 varies in response to rotation of the first rotor 472 around the axis 538 and in response to rotation of the second rotor 476 around the axis 606.

As the separation distance 694 decreases, and as the fluid barrier 676 moves towards the through-opening 594, the chamber 684 remains in fluid communication with the through-opening 594 in the intermediate body 478 and the volume of the chamber 684 decreases. In other words, contracting the chamber 684 involves revolving the second coupling portion (the connector 616) of the second rotor 476 around the axis 606 in the direction of the arrow 678 and in the aforementioned path around the first coupling portion (namely, one or both of the end portions 548 and 550 of the first rotor 472) towards the through-opening 594. Therefore, the torque in the direction of rotation shown by the arrow 678 may cause fluid in the chamber 684 to be communicated through the through-opening 594. The through-opening 594 may thus function as a fluid outlet.

In summary, a volume of the chamber 684 (or a volume of the chamber 692) may be varied by causing the first rotor 472 to rotate around the axis 538, by causing the second rotor 476 to rotate around the axis 606 and thereby causing the second coupling portion (one or both of the connectors 614 and 616) of the second rotor 476 coupled to the piston 474 to revolve around the axis 606, which is different from the axis 538, in a path around the first coupling portion (one or both of the end portions 548 and 550), and by causing the piston 474 to slide along a first linear path, namely a path generally parallel to the generally planar surfaces 560, 562, 664, and 666 and generally parallel to a plane of rotation of the first rotor 472, relative to the first rotor 472 in response to rotation of the second rotor 476 around the axis 606. The aforementioned paths of the second coupling portion (one of the connectors 614 and 616) are around the first coupling portion (one or both of the end portions 548 and 550) because as the second coupling portion (one of the connectors 614 and 616) revolves once around the axis 606, the second coupling portion (one of the connectors 614 and 616) travels around all sides (from the point of view of the housing formed by the first end body 470, the intermediate body 478, and the second end body 480) of the first coupling portion (one or both of the end portions 548 and 550).

When the first rotor 472, the piston 474, and the second rotor 476 move to the positions shown in FIG. 56, the first rotor 472, the piston 474, and the second rotor 476 return to the same positions that are shown in FIG. 49. Therefore, the aforementioned cycles may be repeated, and the apparatus 468 may function as a fluid pump by causing a fluid from a fluid source coupled to the through-opening 592 (or fluid inlet) to be pressurized and communicated through the through-opening 594 (or fluid outlet). Further, because the first rotor 472 maintains a relative orientation of the piston 474 relative to the first rotor 472, and because the second rotor 476 maintains a relative orientation of the piston 474 relative to the second rotor 476, the first rotor 472 rotates at a relatively more consistent angular speed when compared to other piston machines, which may avoid some disadvantages of inconsistent angular speed in such other piston machines. Although not shown, one or more valves may be positioned in fluid communication with one or both of the fluid inlet and the fluid outlet.

In summary, in apparatuses such as those described above, the first rotor or the second rotor can control fluid flow through the fluid inlet or through the fluid outlet. Structures such as those described above may be combined with other structures such as those described above or other structures. For example, in some embodiments, one rotor may control fluid flow through a fluid inlet as described above and another rotor may control fluid flow through a fluid outlet as described above. Controlling such fluid flow may, in some embodiments, facilitate use of such an apparatus as a fluid pumps by, for example, controlling pressure at the fluid inlet or at the fluid outlet of the apparatus.

Further, in apparatuses such as those described above, the piston can be coupled to the first rotor and to the second rotor in various ways that maintain the piston in a relative orientation relative to the first coupling portion, and in a relative orientation relative to the first rotor, so the first rotor rotates at relatively consistent angular speeds when compared to other piston machines. Therefore, apparatuses such as those described above may avoid some disadvantages of inconsistent angular speed in such other piston machines.

Still further, apparatuses such as those described above may be operated without seals because the various components may be machined or otherwise manufactured to tolerances that permit the apparatuses to function without requiring seals that may degrade or fail over time.

In various embodiments, the components of apparatuses such as those described above may have varying dimensions and configurations, and may be formed by one or more of molding, casting, machining, or other methods from one or more of various different materials such as metal or plastic materials as may be appropriate for particular temperatures, pressures, fluids, or other considerations in particular applications. Further, various embodiments such as those described above may include bearings, such as ball bearings or other roller bearings, (not shown) to reduce friction between various components. For example, in the apparatus 468, ball bearings may be positioned between the second rotor 476 and the intermediate body 478, and between the first rotor 472 and the first and second end bodies 470 and 480.

Although specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the invention as construed according to the accompanying claims. 

1. A method of varying a volume of a chamber defined by a first rotor, a second rotor, and a piston in a housing of a piston machine apparatus, the method comprising: causing the first rotor to rotate around a first axis of rotation; causing the second rotor to rotate around a second axis of rotation different from the first axis of rotation; and causing the piston to slide, in response to rotation of the second rotor around the second axis of rotation, along a first linear path relative to a first coupling portion of the first rotor coupled to the piston; wherein causing the second rotor to rotate around the second axis of rotation comprises causing a second coupling portion of the second rotor coupled to the piston to revolve around the second axis of rotation in a path around the first coupling portion.
 2. The method of claim 1 wherein causing the piston to slide along the first linear path comprises maintaining a relative orientation of the piston relative to the first rotor.
 3. The method of claim 1 further comprising causing the piston to slide along a second linear path relative to the second coupling portion in response to rotation of the first rotor around the first axis of rotation and in response to rotation of the second rotor around the second axis of rotation.
 4. The method of claim 3 wherein the second linear path extends generally parallel to a plane of rotation of the second rotor and generally perpendicular to a radius perpendicular to the second axis of rotation.
 5. The method of claim 4 wherein causing the piston to slide along the first linear path comprises varying a separation distance between the second path and the first axis of rotation.
 6. The method of claim 3 wherein causing the piston to slide along the second linear path relative to the second coupling portion comprises causing the piston to slide along the second linear path between the second coupling portion and a third coupling portion of the second rotor opposite and spaced apart from the second coupling portion and coupled to the piston.
 7. The method of claim 3 wherein the first linear path extends generally parallel to a plane of rotation of the first rotor and generally perpendicular to a radius perpendicular to the first axis of rotation.
 8. The method of claim 1 wherein the first linear path extends generally parallel to a plane of rotation of the first rotor and at an acute angle to a radius perpendicular to the first axis of rotation.
 9. The method of claim 1 wherein varying the volume of the chamber comprises expanding the chamber when the chamber is in fluid communication with a fluid inlet defined by the housing of the piston machine.
 10. The method of claim 9 wherein expanding the chamber comprises revolving the second coupling portion away from the inlet along the path around the first coupling portion.
 11. The method of claim 9 further comprising controlling fluid flow through the fluid inlet in response to rotation of the first rotor around the first axis of rotation.
 12. The method of claim 9 further comprising controlling fluid flow through the fluid inlet in response to rotation of the second rotor around the second axis of rotation.
 13. The method of claim 1 wherein varying the volume of the chamber comprises contracting the chamber when the chamber is in fluid communication with a fluid outlet defined by the housing of the piston machine.
 14. The method of claim 13 wherein contracting the chamber comprises revolving the second coupling portion towards the outlet along the path around the first coupling portion.
 15. The method of claim 13 further comprising controlling fluid flow through the fluid outlet in response to rotation of the first rotor around the first axis of rotation.
 16. The method of claim 13 further comprising controlling fluid flow through the fluid outlet in response to rotation of the second rotor around the second axis of rotation.
 17. The method of claim 1 wherein varying the volume of the chamber comprises causing movement of: at least one surface of the first rotor that defines the chamber and that intersects a plane through the chamber and perpendicular to the first and second axes of rotation; at least one surface of the second rotor that defines the chamber and that intersects the plane through the chamber and perpendicular to the first and second axes of rotation; and at least one surface of the piston that defines the chamber and that intersects the plane through the chamber and perpendicular to the first and second axes of rotation.
 18. The method of claim 1 wherein varying the volume of the chamber comprises varying a fluid barrier that extends from a location where the first rotor contacts the housing to a location where the second rotor contacts the housing.
 19. A piston machine apparatus comprising: a housing defining a fluid inlet and a fluid outlet; a piston in the housing; a first rotor comprising a first coupling portion coupled to the piston, the first rotor rotatable in the housing around a first axis of rotation; and a second rotor comprising a second coupling portion coupled to the piston, the second rotor rotatable in the housing around a second axis of rotation different from the first axis of rotation; wherein the second coupling portion has a position that revolves around the second axis of rotation in a path around the first coupling portion in response to rotation of the second rotor around the second axis of rotation; wherein the piston is slidable along a first linear path relative to the first coupling portion in response to rotation of the second rotor around the second axis of rotation; wherein the first rotor, the second rotor, and the piston are positionable to define a first chamber, in fluid communication with the fluid inlet, that expands in volume in response to revolving the second coupling portion in the path around the first coupling portion and away from the fluid inlet; and wherein the first rotor, the second rotor, and the piston are positionable to define a second chamber, different from the first chamber and in fluid communication with the fluid outlet, that contracts in volume in response to revolving the second coupling portion in the path around the first coupling portion and towards the fluid outlet.
 20. The apparatus of claim 19 wherein the piston and the first coupling portion maintain a relative orientation of the piston relative to the first rotor when the piston slides along the first linear path relative to the first coupling portion in response to rotation of the second rotor around the second axis of rotation.
 21. The apparatus of claim 19 wherein the piston is slidable along a second linear path relative to the second coupling portion in response to rotation of the first rotor around the first axis of rotation and in response to rotation of the second rotor around the second axis of rotation.
 22. The apparatus of claim 21 wherein the second linear path extends generally parallel to a plane of rotation of the second rotor and generally perpendicular to a radius perpendicular to the second axis of rotation.
 23. The apparatus of claim 22 wherein rotation of the first rotor around the first axis of rotation and rotation of the second rotor around the second axis of rotation vary a separation distance between the second linear path and the first axis of rotation and cause the piston to slide along the first linear path.
 24. The apparatus of claim 21 wherein the second rotor comprises a third coupling portion opposite and spaced apart from the second coupling portion and coupled to the piston, and wherein the piston is slidable along the second linear path between the second and third coupling portions.
 25. The apparatus of claim 21 wherein the first linear path extends generally parallel to a plane of rotation of the first rotor and generally perpendicular to a radius perpendicular to the first axis of rotation.
 26. The apparatus of claim 21 wherein the piston comprises first and second opposite and non-parallel side edges, the piston coupled to the first coupling portion such that the first side edge is slidable along the first linear path, and the piston coupled to the second coupling portion such that the second side edge is slidable along the second linear path.
 27. The apparatus of claim 19 wherein the first linear path extends generally parallel to a plane of rotation of the first rotor and at an acute angle to a radius perpendicular to the first axis of rotation.
 28. The apparatus of claim 19 wherein the first rotor defines a recess having a position that controls fluid flow through the fluid inlet in response to rotation of the first rotor around the first axis of rotation.
 29. The apparatus of claim 19 wherein the first rotor defines a recess having a position that controls fluid flow through the fluid outlet in response to rotation of the first rotor around the first axis of rotation.
 30. The apparatus of claim 19 wherein the second rotor defines a recess having a position that controls fluid flow through the fluid inlet in response to rotation of the second rotor around the second axis of rotation.
 31. The apparatus of claim 19 wherein the second rotor defines a recess having a position that controls fluid flow through the fluid outlet in response to rotation of the second rotor around the second axis of rotation.
 32. The apparatus of claim 19 wherein the housing defines a generally annular inner surface.
 33. The apparatus of claim 32 wherein the first rotor comprises a curved outer surface positioned to slide, in response to rotation of the first rotor around the first axis of rotation, along a first portion of the generally annular inner surface of the housing between the fluid inlet and the fluid outlet.
 34. The apparatus of claim 32 wherein the second rotor comprises a curved outer surface proximate the second coupling portion and positioned to slide, in response to rotation of the second rotor around the second axis of rotation, along a second portion of the generally annular inner surface of the housing.
 35. The apparatus of claim 19 wherein the first rotor defines a recess sized to receive at least a portion of the piston.
 36. The apparatus of claim 19 wherein at least one surface of the first rotor, at least one surface of the second rotor, and at least one surface of the piston intersect a common plane through the first and second chambers and perpendicular to the first and second axes of rotation.
 37. The apparatus of claim 36 wherein the first rotor, the second rotor, and the piston are positionable to define the first chamber with surfaces comprising the at least one surface of the first rotor, the at least one surface of the second rotor, and the at least one surface of the piston.
 38. The apparatus of claim 36 wherein the first rotor, the second rotor, and the piston are positionable to define the second chamber with surfaces comprising the at least one surface of the first rotor, the at least one surface of the second rotor, and the at least one surface of the piston.
 39. The apparatus of claim 19 wherein the first rotor, the second rotor, and the piston define a fluid barrier that extends from a location where the first rotor contacts the housing to a location where the second rotor contacts the housing.
 40. The apparatus of claim 39 wherein the first chamber expands in volume in response to varying the fluid barrier.
 41. The apparatus of claim 39 wherein the second chamber contracts in volume in response to varying the fluid barrier.
 42. (canceled)
 43. A method of pumping a fluid using the apparatus of claim 19, the method comprising causing the first rotor to rotate around the first axis of rotation or causing the second rotor to rotate around the second axis of rotation.
 44. (canceled) 